Atr ABgTnrclr or Im rm8x8 0r
TACE FAIIOIIEI for the Doctor of, Plrllorophy l.n Pharnacolqgrv
,, Date thosls la preaentcd , .Y\." ,r , r 'll
Tltlo SOl,lE PEABI{ACOI0GIC}L I{ECHAUIS!|S ANP 8EE IITERRBIfiT - grousErP_ oF BIrLmeAPqIpE AS.D s-IIXDBoxrrRI"TqFrqE OX
rIIE CANDXOVASCUIAR SYSTEI{ OT TEE MG Redacted for Privacy Abrtraet approved (l,tajor profesoor)
A etudy hao bcen made to exarnLnc tho intrinaic activL- tles of 5-Ilydroxytrlptanlne (5-m) and bulbocrpnlno and their lnteraction in regard to bLood prctaurc and contrl€- tllc forcc in thc dog. A nurubcr of drugr and procedurec uore uced to evalu- atc these rc3ponsss. ![hc cffects of intravenour lnJectiqne of 5-ET on tho blood prot.uro and contractile force uere forurd to be of a prel.or naturG. Adronal.octmy and nercrpLnlzatlon reduced thcrc roaponsGt. Cocainc and grrancthidina abollrhcd the prersor effect of s-gf on the blood preaaurc of adrenalectmized dogr. 1[hc eontractile foree component of 5-IIT wac reduced by adrenalectory, reserpinization, and adnlnLstratl.on of guanethldine.
Eexanethonium chlorlde, a gangllonlc blocking agent, and tripclennani.ne, an antlhirtamine, trrotentLated 5-Elt re- sponaes. Adminietration of dLchloroiaoproterenol (DCI) reduced the preagor eff,ect of 5-IrT on blood prearure and abollahed tlre contractLle force component. Chemical s1'ntrnttrcctoy and vagotony faLled to cauee any changea Ln 5-ET responaoa. Bulbocapnine caused a fall of both the blood presaure and contractlle force and sqte changes in electrocardio- gram and potageilun Levels of EGrun and heart tissue. lftrle agent lnhiblted the preosor actLone of 5-III and partially reduced the reaponsea of tceted catecholaminer. llhe poasible mechanisrns for inhtbitlon were sought. ChronLc bulbocapnino treatmcnt of dogs led to markcd potentlation of 5-tfT reEllonacs. llhe arq>erLments with ratc, chronlcally treated with bulbocapnine, fal'led to ohow any changec ln the auryival tLme when the anirnals were sub- jected to X-irradiation. SODTE PSAruA@IOOISAL TiECEIIIS}I8 ATD TEE UMERNEIATIOXSIIXP OT BT,r.EOCTPUITIE THD 5-EIDTXXTRYPTAIiIITB ON EBE GARDIOVASCI,IAN, sY TEH OT TEE DG
by
rlOE TAI(oUE
A [EB8I8 rubmlttrd to onffiot stATE uurvBnsrrr
ln partlal fulflllncnt of tho requircmenta for thc dcgrco of
DOq!OR OF PTTIIoSOPET
ilunc 1964 APPROVED: Redacted for Privacy Professor of Pharmacology In Charge of Major Redacted for Privacy Head of Departnrent of Pharmacology Redacted for Privacy
of Graduate School
Date thesls Is Presented Y\"^r "1 , \ta,+ Typed by Ar1ene CIark ACI(MI{I..EDGNOilT
l[hc author's clncere approclation 1r crqrrcagcd to the follodngr Dr. Rob 8. lleCutchcon for hlg guldance, encourage- ment, ttnaly adviee, and aupenrlgion durlng the rerearch and preparation of thig theeigt Dr. lfhoaus D. Darby for hl.c helpful auggestione durLng the research and preparation of thir thcricl Dr. Robert lt. Sager for hir valuable help in prepar- ation of this manuscriptl Dr. Daniel T. Wattc of thc De;rartncnt of Fharmacology, I{cgt Virginia Unlvercity, for making laboratory equlpment avaLlable to be used in these studicst llra. Arlenc Clark for her assigtance wLth thc typtng of the nanuscript. TAAIA Or @DrrBSrS Page
IIITBODUCIIOU...... o...... o . t ...... t t
EI8IORICAL. . . . . c . . . o ...... ? ...... I
DIETRIDIIIIOH IH !{A!&AL...... o.... !...... 1
SYxfEEBfg AUD llETAmIdISf,...... ?,
PEA8HAI$IPGICAL ACEIOHS...... r...... r o. ... . o.. 4 Cardlovaacular 8yrtm...ia...... 4 Bcrplratory 8y1trm...... 13 Suooth ltlurClo. . o ...... o . ., . 13 ALlmgntary Tract t ...... 14 Braln...... r...... l. . ... r ...... r . . .. a . .. 14
POSSIBLE nOIrE Of SEIOIOIII IB XIUIAL PUXCIIOUS... 16
rBE ArlrGorISTg or 5-gYDnoxgrHrPlfAllruE. . o ...... 16
CIrASSB3 Of 5-m ASTAGOffiUER8...... 19 Ergot AlkalotdB and DerlvatlvGt...... 19 D-lyrerglc Acld Dlcthylanldc (rSo1 ...... t... 19 Iadole and Rclatad Ccupound!...... 20 AntlhLetanlncl.....rr...... 21 Adrcnalytie Drug1"...... o.... o o...... 22 Atropinc and Atropl,nc-llke Cmlrcundt...... 22 SYapathctlc lmlnG!. . . . . o ...... 22 Itlrccllancout Agent1....r...... o.... 23
EulbocapnLnc... t ! t...... !. r...... 23
SOllE PBAIXACOIIOCICJIX, ASPEgfg OF POIIAESIII'I fOE.... 25
EXPERIT@II,AL PROCBDITnES nUD REBITLT8 31
EX(PERI"DIEUTAL, CROUP m. I...... r..o. 37
s-tT Rorponror lftGr AdrcnalcctoEy...... 37 5-m RarlronrGr ln RcrcrpLnizcd aninal!...... 4I 5-m RGrlronrGr Aftcr GuancthLdlne ln Adrenaloctmlgcd AnLuralr...... 4l Pagc 5-m Rcrponacr Aftcr Cocal,ne ln Adrcr,ralceto- uized An1mr14...... o...... 44
E(PERXUBIIrAL eROUP !rc. tI ...... '...... 44 s-ET R€slronrco After Eexanethoniun ChlorLdc... 44 5-ET RcBpontos Aftcr l{icotlne.... o....r.. o.... 48 5-m Rctpontar Aftcr lfripclerrnanine...... 49
EXPERIIIBISAIJ G8CIUP HO. III...... '...... 49
5-ET Rccponaer After DlchloroleoprotctGtlol. . . . 49 Chuical StrmPathectcny...... r. 50
EXPE&IIIENTAIT GROUP BO. IIr.....'...... 50 trtre Effeet of Bulbocaprlnc on thc nlood Prearuro, ContraetLle trorce, and Elcetro- gafdLOgrlB...... o...... r...... r.. 51 llhe Effect of Butbocapnlne on the PotaloLratr Levolr of Sorum and [yocardlal Ellluc.... r... o 51
EXPBRIH8HAAX. CROUP trO. V.... r...... t. r.. r..... 53 Inhlbltory lction of Bulboca1mlne. r...... o.. 53
E@ERII{ENTAL GBOITP m. VI ...... 61 ![hc Contracti.lo Forcc and Blood Prcraure Booponac. of, s-Hf and CertaLn Cateeholanlnce ln gulboeapnlnised ArrLnal!...... 61
EXPERII{EHIrAL GROUP rc. VII ...... '...... r.... 61 'i[h; nadioprotectlvc Ablllty of Bulbcap'rLnc ln Ratr.. e...... o r...... 64
DISCUBSIOH AHD C?!rcIrU8IONB...... o. r...... r... 66
SlnelAtrffr ...... o t . . 83
UIELIOGRAPEI. . . . r ...... t ...... 86 LIST OI AABIAS TABLE Page
I...... C![{TROL RESPOT{8ES Of H(PERII{ENIAL AItlIl{Eg ON @}ITRACTX&E FCRCE ASD BXOOD PRESSURE...... O 35
II . . . . . EFTE T OF IPDIryr}IG DRU6S AI{D PROCEDT'RES ON 5-m, 20 ugt1rrg, R89DoN98s...... r.. 38
III....TEIE C$HTRACTIIJE FORCE AI{D BI.oOD PRESSITRE RESPONSES OF s-ET IN RESERPINIZED A}IIIT{ALS. . . . 42 fiT.....5-IiIP RESPONSES CIN COIIIrRACTILE T'ORCE A.}ID EIOOD PNESSI'RE ATTER MODITrINC DRI'GS..Q..."' 45
V...... IlTFlfilgIC ErFECT Of BITLTeAPNINE ON @NTRAC- TIrJ0 FORCE e&{D BrOOD PRESSURE...... o. . 52
VI (A) . .ABSOLIXrE SERITM POfAggIIn{ AbID AVERAGE CHANGE ltllE TII,iE AEIER BITLrcCAPNINE 50 mgAg...o.... 54 vr (B) . .eEAttrGEs rE POSASSrIm C$NCEEITRATTOI rN mg/LOO gr0 I{ET TISSUE OF rHE l,fYOCARDrIm.,.... . 54
VIX. . . . rlTIif,fBXlrION OF CO}ilTRA TII.B TORCE A}ID BISOD PRESSI'RE RESPONSES OT IIIIE E(PERIT{EDTTAIJ A}tI![Es A}ID POTASSII'M CHTORIDE APTER BULBOCAPNINE 5O rngZl<,g...... r . . . . . 57
VIII. . .TIBE ETPEC:T OT }IODITrlsG DRIreS ON IUHIBIIETO}T OF 5-ITT RESPONSES BT BULBOCAPNINE...... 60
IX.... .COIiIIIRA(IIILE TI)RCE AUD SIOOD PRESSITRE RESPON8ES OT THE E(PERIME}TTAI, Al{I[VEs AETER CHNONIC AD- MINISTRArIOX OF BITLEOCAPNINE...... 62
X...... RADIATION PROTECTIOU AETER CHrcIltIC ADI.[INXS1[RA- TION OF BtIrBOCAP}IINE...... o o.. '...... 55 I.Igf OT TIGURES Flgure Page 1... -Maln Patlvayc In tlrc Blorlmthcrlt and tlatrbo- llm 5-Uldroryrt,rlptanln€...... r o.. r...... 3 2,...Control Rerponrcr of s-Ef on Contractllc Forcc and Blood FrerrurG...... o.. -...... 36
3. . . .Cm;rarative Reaponacr of 5-m, 20 ug/t.g, on tho Elood Prcrturo Aftcr tlodtfytng Drugr and Proccdur€8...... 39 4....Cmtrrarative Reaponccs of s-ET, 2O ugtlr,.9, on the Blood Pretsure Aftcr ldodlfylng Proccdurcr...... 4A 5....![he Contractlle ForcG and the glood Prorgure of 5-m ln Rererplni.zcd Animale.t...... 48 6,...|!he Blood Preslure Rcaponee of 5-Hl After Itodtfytng Drugl...... o . . . . . 46 l...,'l[he ContraetLlc ForcG ncrllonrc of 5-m Aftcr Ho'dlfying Druga...... r ...... 47
8. . . .Changel in Concentration of Serum Poteultrm Aftgr Bulboca;xrine 50 eg/ltrrg...... r...o...... 55 9....InhlbLtLon of Blood Frclrurc Rcr1rcnra. of tha Ercpcrlmental Druga Aftcr Bulbocapninc 5o urg/*g. 5g l0...Inhl,bltl.on of, Contraetlle Force Rer;ronres of the Ecperlmental Drugr Aftcr Bulbocaprlne 50 ng7tg...... r...... r. r...... t 50 1l. ..lfhc Contraetllc PorcG and the Dlood Prerrure Rertrpnres of s-Im After ChronLc Adnl,nistratLon of Eulbocagrlnc 25 trrg/*g...... 63 gTATTTEtrE OF PNOaI&DI
Ihc ehanger Ln the clrculatl,on follelng Lntravenour J.nJcctlonr of S-hydroqrtrlptanlne (5-Ef) in cxlrrtnontrX. anlnalr have bocn only Lncmplctely analyecd. BoEh rirc and fall of the blood prcmurc follwlng lntravcnouc inJec- tlon of . S-ffi hrve b.rrr rqnrted. l[hG affecte of 5-E.F on tlrc blood prat.ure have boan attrl.buted to perlpheral vaaoconrtrletLon and a hlrtaninc rclcale nechanl.&. In rcgard to thc cff,oetr of 5-Ef on thc contractllc forcc of thc dog heart, vcry llttlc, Lf any, work har been dono.
A nunbcr of s-ET antagonirtr havc bccn rtudl.ed. Onc ruch agent ts bulbocaSnlnc wht ch har boen knowrr to pro- duec a catatonLc cyndrone ln a numbcr of spccier. Ihe ncchanis rer;rcnrLb1c f,or thc catatonla lc not kn*rn, aI- though roao invectlgatom have attrlbutcd thtr to a csntral mechankm. BulbocapnLne hat bcon knwn to havc an fu&lbltLng cffect on the prGr.or rerpontc of rmc catecholrqlnea cuch ar eplncphrlne. Eoever, not rrntLl vcry rccently waa lt rGpoft,cd to have 5-m antagonl,alng aetlvity. !!ho blocklng actLcnr of thla agent wac rclrcrtnd by oae lnveetigator to be due to thc inhtbltlon of alpha- reccptors of the adrcnergLc sylton, which 1r raanifeetcd by a ro-called "opJ.ncphrlne ro\rors.ll. " On tlre contrary, other lnvoetLgaton havc f,allod to rhov an ,cpLnephrlne rGr/erral. o ![hersfore, t]rc lnf,ormation concerrring t]re blocklng actl,on of ttrlr agent il lcarce, fragrmentary, and eontradletory. I*re purposo of thi.a work Lr to ttudy 5-&.l and bulbo- eapnlne ln regard to theLr Lntrindc activitlor on thc EKG, blood preaaurG, and the nyocardlal contraetile force of the dog. Poulblc medranime for there actlons are rought. 'l!he rerponsee of S-Ifl and bulbocapnLne bofore and aftcr auch agontc a. rGrerplnc, ganglionic blocking agonta, adrenorglc bloclcl.ng agentr, antlhLstanLnlc and other agaats of slnllar naturo arG rccorded arrd crl.tlcally examlned.
lhe uechanlm of bulboca;xrlne lr*rlbltl-ng actLon Ls atudicd wlthout onerlookLng tlre lnaclbLllty that lt uay be dua to tho Lntrlncic propcrtles of thlr agent, Inhi,bL- tion due to lnterferonco wltlr normal eatLonLe exclrangc hla recently been portulatod for a number of adrenerglc bloclc- Lng agentg and tlrlc 1r exanlnGd ln reratlon to bulbocapnLnc bLoeking aetlon. INTRODUSrIOU
TIISAORICAI, About onc hundred yGars ago Lt war dsmonrtratcd that the vaeoconctrl.ctlve power of blood lncreared vhen lt clotted (53, p.563). Stevens and Loe were among the flrrt invcetlgatore to flnd that thlr vae due to thc appearanca of vasoconetrl.ctive cubrtances ,.n the clotted blood l77t . In the follryl,ng years Rapport, Green, and Pago uGrG ruccGrtful ln lrolatlng and later cryrtalllzing a eubrtancs frm blood senrm which wae subccqucntly ldcntlficd ac 5-Eydrorytrlptanlne (s-fT, Scrotonin) cmploxod wlth crcatlnc and eulfurlc acLd (631 62t 611 60). Soon aftcr, Bamlln and Plaher urGrc abla to rynthesLzc 5-Hydro:rytr1pta- mLne (35).
DI$IRIBIIIION XN llAItOlAL'8 S-Eydrorytrlptamlns Lr found ln all tl,scuee containing enterochromaffLn celle. It la found in largeat quantltler in the mucour mernbrane of thc aaatrolntertl.nal tract. lthe pylorl.c portlon of tha gtmach and the uppGr part of the aoall intcatinc hold tho largeat amounts of 5-IIT in thc allnentary canal 126, p.361). P1atelets rtorc the naJor portlon of 5-lIT in thc blood 167, p.124) . lfhe anount of 5-BI in the platelet-free placma 2 ig almost nil, Ttris ig due mainly to rapid absorptLon of 5-IIT, trnrticularly at body temperature, by the platelete. A decrease of temperature to zOoC, a rise in the PH of the suspendlng medium or some druge partJ.cularly applled in low concentrations have been Ehourn to stop the uptake of 5-IIT by the pLatelets (4) . Ttrarg and Page v/ere first to find 5-IIT in the nervous system (83). The diatribution of this amine was shfrrn to folLotr cloaely that of norepinephrine. The pineal gland and certain gubcortical nuclei contain the highest concen- tration of 5-HT in the nervoua syetem. The cerebral cortex, cerebellum, spinal cord, dorsal and ventral rootg, and slrmtrnthetic Aanglia contain Llttle or none (67, p.125).
SY.NTHESIS A}ID ITIETAEOI.,ISI{ Tryptophan ig probably the lnrent substance of mogt of the naturally occurring indole derivatives, including 5-IIT. Udenfrlend and his colleaguea, etarting from trlpto- phan, have worked out a scheme for the possible bioJ.ogical aynthesig of this amine (87, p.126) (gee Figure I). 5-IIT Ls oxidized by amine oxidase to an al.dehyde and then further oxidized by aldehyde dehydrogenaee to 5-Hy- droxindoleacetic acl,d (S-nfae) which is excreted in the _ ^.. !o" UtJcH2crrNH2 I H tryptophan ,", | - coo, Gp",'*L,,,lWcH2co t{H t-hydroxylndole pyruvlc acld 5-hydroxytryptophan ,- - (s'J'- -rrp) (b) Ho I o-s1ucuro"{:}di-il'cH2cH2NH2 r N-acetyt-5-tr ;-il;il";;e\A,r/ - (f) HI | | 5-hydroxytryptamin" | / 1s-ttt) - I V
o .rr.r,LL o*tll -ftr -T cH2 clt2 NHco' cH3 9O' H 5 -hydroxyi ndol ea ce tal dehyd e N-ace tyl -5 -me thoxytryptamlne I (d) (melatonln) l I tto:rf'',-cll^coonv
PBARITIACOIOCICAL ACIIOUS
Cardlonagcular Svrtem llhe cardlovarcuLar rclponsee to 5-IIT are hlghly varJ,a- ble. Specier differencee and experLmental condLtions are the nort colrlnon varlablca. fhe cff,ect of elngle LnJectlonr of S-tlT on dog blood presrurG uay conslat of three pharcrr 5 an LnLtLal quLek fall wlth bradycardla follqred by a rLrc and then a prolongcd deprGttor reetrronrc of mallcr tragni- tudc ttran thc prcr.or reaponrc (81 52, 9.721. llhe rnaller lnltlal fall 1r a "Bozold cf,foct" whlch can bc aboliehcd by vagotmy or atropLnlzatlon, but nclthcr of there alterr thc eccondary prolongcd doprcrlor rotpontG. Page and tlcCubbln havc ruggeeted ths f,ollonlng ar a mechankn for the pro- Longed deprearor rGatr>onoer (1) releaee of cndogonou3 hlrta- ml.ne by 5-1f,f1 (2) perl.pheral lnhtbitl,on of ncurogonlc valoconrtrLctl,on, and (3) a doae-relponte relatlonahtp that, in rorae preparatLonc, will rhow whether prctsurc wtll rlrc or faII (5S1 . lftrc rlae ln blood prcsaure could be duc to increalcd cardiae output and perlphcral varoconltrictlon
(55). l{cCannon and Eonrath have reported an incrcaae Ln pulnonary and syetcmlc vaccular regLrtance whlch la qulckly follorred b1z a rlee ln cardLac output whLch helpcd to naJ.n- tal.n thc prelror rGrlronae to 5-m ln dogc 142) . lHrcee lnvcotJ.gatorr have conelctcntly reen a prctsor rollrontG whancver 5-ET waa LnJected lntravenoualy Lnto the pulmonary artcry of pentobarbltallzed dogt. Attentl.on 1r callcd to nunGrou! rcportr of prcaaor, dcpreaaor, or cmblnationa of thcae offectr preaent l,n the lltaraturc. ![trte varlablllty can urually be cxplaLned on 6 thc berj,r of thc degrec of nGuroEGnlc varcular tons prorent prlor to rcrotonln lnJcctlon 192, p,72). Ilre arterlal prGmurG rorponre to Lnfured rorotonLn nay vlry bottt qualltat,Lvcly and guantltlvcly ln tbe rrr&c Dann€r ae tbet of a dngle lnJeetlon. In dogrc, thc re- lponlc to lnfuri,on of rathGr largc anountr of rcrotonln la ulrally of a dcprcator tftr (SS1, Ihc antlhtetaulnlc drugr have bocn ltrczr to Lnhlblt or proyGnt tho deprcrror rGqloare to rorotonln i,nfurlon t hwrver, thoy ghorod no actloa on the dcpreror rGtponrG produccd by rlnglc inJcctLonr (SS1. Ilblr nay lnply that although tJro relcatc of, end,ogrnour hlrtenlnc b1z trrotonin contrlbutor to tlro rGqlonrot produecd by Lnfurlon, lt atrould be dlrregardcd aa a lrcrlblc nochanLru for thc eccondrry dcprctror 1fialc produced bty a t{nglc LnJectlon of tcrotonln (8) . Euneg and Walarzek havo ruggcrted that the preraor aetlvLty of 5-H could bc a dtrcct reault of thc rlmpatho- adrcnrl etlnulatlng actLvlty of hlrtanine (81 9) . Elrtarnlno har bccn rcportcd to producc a pra.ror cffcct Ln a nunbcr of, rpoclct (81). 'lllrc prcetor rGtlronre of hlrtanlnc ean be caurod by tr*o neclranlmrt atlnulatlon of qmpathatlc ganglle (lncludlng ad,renal ncdulla) leadlng to dkdrargo of 7 cat.cholenlneg frm tlro adronrre and, b1z rcloarc of trenr- nlttar eubrtancor frsr thc rlmlnthctlc atoror of portgcng- llonLc adrenergLc flbors (8X) . 'l$rc enrldancc for thlr ruggertl.on war provldcd when oecperl,mcnta with adrenal- cetonLzod anlmale falled to empletcly abolirh the prcrror rcrlpnao uitlr hirtauinc, hqroner, rueh rcllron.e waa no longer cvLde.nt after protroatnent wlth eocalna and rerer- pLnc (81, 43). A nrmbor of emtrrorrnda luch a8 ro.GrPlnc, grranothldine, coctlne, hcxancthonltn, and nlcotine are of rpcci.al valua Ln the dctermlnatlon and dkcud.on of thc nodr of actlon of, hlrtanJ.nc and s-E!f or tlrcLr Porrible interaetion. llhercforc, a rhort dllcucrlon of thclo ca6- poundr at thir potnt could Prove to bG of subrtantlal hclp to tbr rGador.
Rcrcrpfnc lr a traut olfi,a altalold uhich har bccn chryn to eaurc a lotr of catccholanlncr frm tlrc adrcncrglc nGIrvGt and pcrlphoral tirrucr (32, p.l7{, 17}. It alro has bGGn rcported that thlr agent grcatly roducer tbc 5-B contont of thc braln and other rtructurct (32, P.174) . 'l[ho lcvolr of, 5-B rnd norepLncphrl,nc in thG braln of lcno cpccl'cr declinc in parallcl af,ter rclcrplnc (73) . 1[ttc htghcrt cqr- ccntratLonr of there tryo anlno. wGrG found in thc hylrcthala- mur, the rotlcular formlrtlOn and the ataa lrcrtrcmA, llhslo I rrorr lrG ral,d to corcopond wlth thoro wblch, aftcr olcctrl- eal rtinulatlon, clur. gcncrallzcd rlmpathctic dlrcharge at the pcrLphsry (32, p.174) . Thc tnportanee of the ccntral and pcrLsihcral effceto of rercrpinc lr regrulatcat b1r rolatlve ronrLtivitica of ths central and perlphcral rtorer of norcpLncphrLne to tho re- lcarLng actl.on of thls drug (32, p,174) .
lftrc catocbolanLne rclcadng effcct of, rercrpl.ne haa bccn rhqrn to bc dcpcndcnt upon en lntrct rehtionahl,p bc- trrecn tlre adrcnal rqodulla and thc braln (33), A catcchola- mlnc rtloarLng offcct lndcpcndcnt of ttre crntral ncnroue ryttm, througlr clreulatory nrbrtancct, har aleo bccn doCI- onttratod (741 . !firoreforo, lt tc ruggertcd t]rat the lmor- ing of, pcrllficral catccholauLnc Isvc1r resultr frm a dlrect ar wcll er e ecntral cffoct, oxcrted by rcrorplne (2a1. It *rould bG notcd thit a lrrgc varlatlo,n Ln thc rentL- tlvltl,cr of, differcnt anlno ltorcl, to relearc by rctcrpLnc 1r For LnrtancG, Ln rabbltr, altlrough rcaerplno .prercnt. could alnort eonplotoly romovc t}re catccholamlno rtorcl frm thc heert, braLn, and adronalr, the ttrrcrbold dotc varj,od for cech orgur (32, p.174). l[harcforc, heart, braln, and adrcnal rtorcg rcqulred, rotllcctlvcly, 5 ugftg, 0.1 mgl In dogr 48 hourr aftor t..!re LnJectlon of guancthldlnc (44) . lIhe meehanlcn of deplcttng action of guantethldl.ne appcars to bc dLfferent frm that of rescrpLne. Guanothi- dine, unllke reoerplne, doee not eaure deplotlon of cateeholanlnee ln the ad,rcnal mcdulla. Anotlrcr l,nlprtlnt dictLnction lc tbat guanethldl.ne talls to rcleaaa norepl.- ncpbrine fro the amlne-contaLnlng granuler of borrlne eplcnic nelr/e (90, p.494) . It J.e, theref,orc, PossLble that tlc releara of eateeholaurlno b1r guancthldine, I! $S, la oecondary to an r:ndeflned oxci.tatory effect of thla egent on adronergic nertre tj.rsuc 132, p.208). Anothcr agent whleh producce the guancthldlnc typo of, actLon ls cocaine. Cocainc har becn rtudied cxtenolvely ln rogard to lts effecta o,n the actlon of qmlnthmdnetLc rmlnggi. It 1g reported to lncreare the prossor aetion of norepinephrLne (43). Trendelcnburg rtudled the ratc of, dlsa- plrcannce of norcpincphrlnc frm thc blood of a rplnal cat Ln the pr€aencc of eocal,ne and found that ttrc lntravGnous inJectLon of norepinephrLnc ln there anlnalr raainod for a much longcr tLnc tlran ln anlmalr wlthout eocalnc (82, P.64) . Dtaqntl].an har euggertod that gLncc norcplnephrlne Lr taken up try ctoragc gLtet nGa.r s1m1nt*tetlc nenrc cndtngr, the actioa of cocalne ln lncrearing tho Prssror of,fest nlght 11 bc due to prcrrcntLon of thLr uptakc (43). lfheroforc, tt 1r eoncludcd that although both rcarrplno and cocalnc c&uto nulr€rlGnrltJ.vity of, rympathetLcrlly innenrated organr, rororplne rolearea eatcclrolaminer frm tiraue ltorcl, wharcal cocalnc prevcntg bot'h tlroir rclearc and uptaka l.n tho tLrruot (95) . Ihercforo, the tro cmpoundr produce a c@on cnd rclult through trro dtf,ferent ncchanJ.ml. A].ro of lntcrcat La thc actlpn of cocalnc on another aml,ne, tyranlnc, lllhc prertor aetlon of tyrauJ.nc Lr abol- trhcd folloul.ng a cocalne tnJactlon. 8l.nce tyramLnc hae been rhown to excrt its proaror actlon by rolearing norepi- ncphrlno, it wat luggcrtcd that cocaLno nlght prevcnt thc actLon of tynninc b1r rtopplng ttrlr rslcare (11, p.304). f,cxamcthonlrm lr a qurtemary armonirn ealt rhlch ir kn*m to be a copetLti.vc tntagonlrt of acctyldtollne at ganglLon synrprcr and thereblt prcvcntr dcpolarlzatlon of the portgangllonlc nemot. Erywer, lt doer not dcprur ttrc reloaro of the acctylcltoltne tranmltter at tlre tyna;l* ter, rnd, unltke nlcotlne, docl not eaule an j.nltlal cxcl- tatLon of tlre ganglton (58, p.55). llhs efficacy of thc bloq)s 1r ral.d to bc dcpendont u1rcn thc quantlty of eccty- Icholino releared at thc qtrtapi . lfhc prcator rGtlronrc of hletanlno aftcr hoxanethoniua la reported to bo narkedly L2 potcntlatcd (81). ftrir potcntlati.on could bc due to the pcripharal cnd organ devoloptng hyperleneltlvlty to ePl- nepbrinc and norepl.ncphrl.ne, and whcn hLrtaml.nc releaees ondogcnour cplnephrJ,nc and noreplnel*rrlne a lrctontiated prertor cf,f,oct Lr rcsn, l[!he hyporrcnrltlvlty war r]rqwrr to c:rcced that caurcd by pregrnglJ.onle nervo lGctlon, but lecc th;1n that eaured bf PostgtnglLonlc nerye rcetion l2L, P.33). Iho grcatcr cGngLtlvlty caurod by gangllonte blockade, ll cmXsrod rlth PrG{Iangllonj.c norvG .Gctlon, rnlght lndLcatc that hypepcnrittvlty 1r duo to thc lancred amount of cplnc$hrlne and norcplnophrLne ln t[c ragl.on of, t]rc ef- fector co!.lr (2I, P.34). tlhG .octlonlng of preganglJ'onLc cervj.cal qmpathctLc nenrcl reducce only tlrc local rclcaro of tbrrc anlnel, rlhcrott gangllonlc blocklng agcntl havc widerpreed actlog on alL organc lncludlng thc adrsnal mcdulla and probably alro d.oprom the lqrcl of clrculatlng anlncr (2X, P.34). In csrtrast to hcxanot*ronlum, niCotLno !.e reportcd to have a blpharlc galgllonte blocklng aetLo{r' l[trc firat phap Lc a dcpolarlsatlon aecomlranfcd ry excJ.tatlon and f,oLlsod by a block. tl,trlr leadr to thc eecond phaac, vhtch Lr a cmpetl.tlve bloek (58, 55). Elrtaulnc hac bcen rcportad to losc ltr prareor aetlvtty durtng thc flrrt 13 plrarc of thr nLcotlnlc block (81) . Eqrwcr, I mlrkcd potcn- tl.atlon of hl.rtaninc prcrtor rctlronrc ir reported durLng thc sccond phaao of nLeotlne actl.on (81) . ftre prlm4lr lntcrert of thle lnvcrtigatlon 1r the actlon of S-ET on the cardlovarcular tyltom. f,ccncr, a brlcf dlrcuulon of thc aetivLtl,cr of thLc agcnt on tho otlror emntlal body organs rrar folt to bo ncccsrary to frnillarlzc thc readcr wLth ltr general actlon. Rcrplratorv Svstqrr DurlaE tho intravcnout infualon of, 5-ET, hype4noelc and almocLe rcrponror raay bo goen (67, p,131) . IhG hypcr- Imoefe rcrponfGt are bclteved to be due to rtlmulatlon of chonroreccptore, eLnco thero rGlPontGt atrG dtntnirhcd upou rcctlonlng of the carotld rlnut nGrve 167, p.131) . 'lflte a;xtocic rclponicr Dty be crurcd by the eti.mulatLon of receptorr bctrocn tlrc groet vci.ns and the left atrLr,rml hqcvor, l portlblo central aetlon rhould not bc orrorlooksd (50) . Soooth l{qacIc Enan and Schild havc rcportod that ccrotonin producor a parcrful contractl.on of annLotlc ulsttbrtno of lneubatcd ehldc (241 . Sl.nec tlrls neuahrane Lr froe of all nerve flbcrs, any eontractLone may tndlcate that 5-ET haa a L4 dl-rect effect on mooth muecle. Xtls abtltty to produce contractLon hae been ahown on the nnuunalJ.An lsnooth muccle Ln tlre alJ.raentary tract, utorue, urlnary bJ.adder, uretcre, bronchial tract, pupl!, and nlctttatlng meenbranee 124, 67, p.132) . Ali-mentarv Eract 5-m cauaes a contraction of the longltudlnal nuscle of isolatod rognenta of guJ.nea Plg j.Leum (67, P.132) " lltrig cont::action ic only parttally blocked ry atropl'ne and d-lygcrglc acid dlcttrylanldc (IJ)s) 167, p.13?) . oaddun and Ficarellt have concluded ttrat thcre arc tro typee of reecP tors ln the Lnteatlneer D-roeeptors, blocked !ry pheno:ry- bensarnl,nc (dlbenzantne) and IeD$, and tl-reecptore, blockcd by nor$hine and cocalna (3o). BraLn Itre diacsvGry that braln contalna largc quantltlcs of rcrotonin lnttlatod eonriderable interoat about itr role ln the central nGtnoua ry.t€o (83, 2, p.6L3) . ![he htgheat concsntrat.lonr of thlg lmlnc ara fotrnd ln thc braln lteo, rpccifLcatly thc bypothalanue, and occur nainly tn the boqnd form, Reaerplne La believed to exert ltr central aetlon ln thcee regione whoro the rerotonLn lcvol ls hlghert (7Or 4). 1s EraLn rerotonln rhoru a hlgh degrec of rendtlvlty to rcrcrpLne. Shorc ct Ef. havr armarigad ttre actlon of rercrpl.nc Ln tho braln ar followrr rftcr onterlng tho hraln very rapldly through an unknqrn mcchanlm, lt 1r- rsnsrrlbly affcctr thc rorotonln bindlng al.tcl and thcn dlrappean (711 . lftrls trr follocd by tlre releaec of un- rtablc frce scrotonln whLeh, lnrtcad of belng rtorcd, rcualnr ln a frec, pharnacologlcally ectlvc form and pro- aantr the braLn tLrruc with a peralatant but low coBCGD- tratLon of frec lsrotonl.n. ftrc cffect of rcrcrpine contln- ues rrntLl tlrc blndlng altst regaln thcLr blndlng calnclty or until ncr aitor arc forlrd (73). BrodLe and Shorc have ruggorted that scrotonin Lt a chcmlcal mcdiator ln tle braln (6) . It war furttrer domon- rtratcd that both pararlmlrathetlc and elmpathetlc cyetcmr aro prGrcnt Ln tlre braLn atcn (6). It 1r thcroforG rug- geatod that eonotonln lr the chanLeal tranamittor of ncrye lapulaea to the centcrg of, the paraq/rnpathetlc ryltGm. &accrpLne lnduccr lta pararympathctle-llke effoctr bpr rc- lcerlng a low but perrirtant conccntratLon of, Eorotonla to actlvate the pararlmlnthctlc contcm (6) . |!hc almpathetic ryrtcm 1r beU.cvcd to bo nedlatcd by noreplnephrlne, wht ctr ha,r bccn forrnd ln alore asrocl.atlon L6 wlth aerotonln !n the braln (6) . PO8BIBLE ROI.B Of SBnOIOtrIn If }iEN'IAL fUtgfIOgS 'llhors Lr no dcflnite proof of rerotonln control of uental proeea.cs, only a body of evldcnce that lndlcater that taaperlng wLttr tho functlon of thlc subrtanqc leads to bohavloral changos Ln nan and laboratorT anjmale. In addltton, other cmpoundc that ean antagronl.za or poten- tLate sarotonln have becn shq*n to influ€nce the peychl,atrLc atate of tJre hunan being. A number of thcae ccntrrcundr ara kn*rn to lnterfcre wlth rarotonin actlon ln vltro cvcn though they do not havc a rtructural relatLonrhlp to lt tnd cannot be considored ono of Ltr antlnctabolLteE (9e, p.656). lBrece agcntr alao caurc a rpeclfLc deflciencY of aarotonl.n on icolated sooth muecle. All of thlg nay ruggest that the mcntal effectg of thocc dnrge may arlee bccaure thcy drango the eeroton!.n lcvol of, ttra braln. TEE ATITA@HI8II8 OT S.EIDNOIil,ITKTPITAIIIIUB 5-ET antagonLrts havc bcon ehan to glve dlffcrant regultr when torted on varl.our organr. Sme derlvatl,vea of ergot alkaloldr have bron roported to be very potcnt +ntagonlrte of 5-ET Ln thc rat utoru. or rabblt Glr pcr- fusGd ulth ralt eolutlon, lrut tlrc cane chemlcals wcrG not 17 lrctcnt antagonlrtr of s-IIf on tho gulnoa plg ller:n l2?l . In an attmpt to oxplaLn thl.t variablllty, &ddum gg g!. have ruggerted thc cxLrtencc of trro klndl of trypt.plne reccptora (29, p.49). Ono ic found ln the aurclo of, rat utcrug and the rabbit ear and 1r ead.ly bloclccd by thc actLon of d-lyrcrgl.e acl,d dlothylamLde, gramLnc, or dllty- droorgOtanLne. A oecond reccptor wa. found ln tho gruLnea ptg LntcrtLnc and war not ccrily blockGd b1z euch drugl. Al a rosult of further lnveatJ.gationr, Gaddrm and Plearelll rcportcd that thc gutnca plg lleum csrtaLncd two tlpcr of recoptora rcnrltLve to 5-m and dlf,fercntlatcd thcn through the urc of dlffcrent antagonlrtr (30) . AccordLng to thcro autlrorl, onc reccptor typc (t{-rccePtor) le probably ln the nGrvoua tlrue of, ths Lntertl.ne and could be blocked by morphine, atropLne, eocaJ.ne, and mcthadone. llhc cccond typa of rcceptor, located ln thc mootlr mulclc, 1r bloekcd try drugr euch ac dl.banzyllnc and S-bensyloxlgramLne. SLnca the dtff,erantLatLon of 5-m rocoptorr ln dLffercnt orgrnr lr of great valuq in charactorlzLng thc typc of actLon of 5-ETr tt 1r lnportant to dctcrmLne whethor thc naJorJ.ty of, 5-Ef rcccptors in tho organim belong to Dl- Or D-roceptor tlz;ler or one entirely diffcrcnt from thqn (30). Ilnfortur- atcly, thc rceoptore to only a ferr organ. havc bcon 18 LnveatLgated and very llttle Lr knorn about the receptore to such lmportant organe ac braln (301 - Anottrer lnernr of, cLaastf,ylng the 5-E'T drugo is on thc bacis of tlreLr cmpctltivc or non-conpGtl,tlvc t1r;le of anteg- onlrsr (34, p.403). EouGvGr, thlr elacrlfLcatl.on tends to oner-sinpllfy the cmplcx J.ntoractlon Lnvolved betvcon 5-tf and ltr antagonizerr (34, p,403). l,lany druE interastionr whj.ch involve an agonLrt and an antagonltt have a cmlrotltlvo naturc (34, p.404). ![hLc dooa not lnply that the Lntcractlon te talclng placc at a coron rcceptor rl,te. Furthernorc, nrny drug LntcractLonr bctrcon a rLngle reeeptor and trro druga whlch are antagonl.e- tic arc found to bG non-cffiPGtltLvc (34, P.404) . Gyemclc haa ;rclnted out that thc maJor dlfflculty in the rtudy of tlre intcractlon of 5-8ts and 5-E antagoalstg 1g that the related cnzlme-type receptor tyrteurs are not avallablc for lnvertigatLon (34, p.404). EG har dLrcredLted tho ure of Lrolatod organr for antagonLm rtudlcr rincc it can only cxclude the exLrtence of one or anotlror tyrpe of anta,gonlm anrd, in nany inrtanccr, thc oxact ty1rc of antagonLstlc interactlon, or the rltc of intcractLon, rcmalnr obocutre. t9 GIJL88E8 0r 5-m AmA(prIZEnS Ersot [krloldr and Derlvatlvcr In 1953, FJ.ngle and Gaddum found that crgotamlDo Gn(- ---- orted pronounced 5-Elf antagonim (27t . A moro detallcd ctudy of the antL-S-B potencY of natrrral and dehydrogrenatcd ergot alkaloldr f,ollowed and rerrealed that mort of tlrcro alkaloldg rh* a hlghly aalec- tlve action agalnrt thc 5-BA contractlon on the irolatcd rat uterur (12, p.L27l. l[hcre rtudlor ehmed ergonorrlnc and nothylcrgonovlne to be hlghly potent 5-tfT antagonizLng lgcnts. !f;hc numbcr of crgonovine groups and the natural and debydcogonatcd alkaloldc of the ergotoxl.n group exhlblted, rerpGctlvctr y, veaker and realcert potcncler (12, p.121) . D-lvrorqic Acld Dlcthvlanldc (LgD) Follqrlng the lntroductlon of L8D ar a potcnt 5-m antagonltcr, Dl&erour LnvcrtJ.gator havc ttudled thc cm' paratlvc potoncy of thlr eoporurd and lts dcrLvatlvee t29, p.49t L2, p.128). tIhG etudLea have drorm tlrat IfD antagonlacr tho act!.on of S-E'T on tlre.rat utorue (74). I'blr antagonlrn wrr fowrd to be speclflc, aLneo the con- tractLqr caured bryr acctylcholLne and orytocin IrGrG not af- faetcd. Xn addltlon, thc Lnteractlon wrr ihown to be 20 ccntrGtltl.ve. Iarger dorer of IfD havc exhlblted a block- Ing actlon on thc rabblt car, the rat kidney, and partially on the guLnaa plg tleun (58). !!hc antagonlzlng ectLon of I8D var later clerrj.fLed ar a blocker of D-rcccptor, whlch rar tlrought to be locatcd on plaln muscle cclla (301 . IrSD it alro regardod cs the mort potcnt and probably thc most relcctLvo agent ln blocklng thc vatoeonatrictor actlon of 5-m on narry vagcular ryrtcmr (31) . Iho cffect of I8D on thc nenrour ryrtcm hac been ex- tcndvcly rtudlcd. lfhl,l cmpound le an errtreeaoly potent halluclnoganlc agent. BdGvGr, no gatlrfactory corrclatLon har bcen found bctwccn ltr halluclnogcnlc actl,on and anti- 5-E'8 cffcctr (54, p.310) . Indolo and Related Compounds Ehc indole dcri.vati.vcr wl,th an antl-s-m actlon are nrucrour. llhcy lnelude dorl.vatlver of indolc, derLvatLvea of granLnc (3-(anlamothyl) tndole), and dorlvatLvor of trlptanlnc (3- (2-amlnootlryl) tndole) (3 t 22t 72, 96) . All tlreac alkaloldr arc lclr potcnt antagonlzGrt than tho alkaloidr of tlrc crgot t14n, which alco rharo an lndo1c cholcal strueture (3). 2L Antlhirtanincs llhe obrcnratlon that rcrotonln roey be rclcarcd alonc or along wlth hlrtanlna ln fmc allcrglc or anaphylectLc rltuatlone ln expcrLmental anLmelr Lnlttatcd thc rtudiee of antl-rGrotonin acti.vltler of dlffcrent antlhirtrnlnGr. Among thoac whlch bave bccn rhqrn to ;roerare thero prolrcr- ties are phonothLazinc derLvatlvcr ruch ar chlorprmazlRe, prmetharlne, and trinephaalnc (35, p.73 t 571. Of thtr group of eorpoundl, chlorprmazLnc har rsrrealcd a hlgh degrcc of S-ffi antagonlmt. Chlorproaglnc uu found to bc ono of tho moat potent S-IfT antagonirtr on thc lrolatod rat uterur and on the pcrfurcd perlpheral vcreclr of thc rabblt 147, p.75). lrlpelennamine (pyrtbcnstmlne, PBG) har bcon roportcd to antrgonLze tbc aetlon of htctrnl.rc on tho blood vcrselc and rnooth nuacle. fhla cgent har becn chornr to antagonLzc thc cplnrl*rrinc rolcarlng offect of hlatauLnc (41, p.570). It tr porelble tlat hlrtanlnc eoulrGtes for r6c rcceptor aLtea ln thc ncdullarT cellr, exortlng ltr actlon by bclng attadrod to thrrc cella. ![he action of PBE 1r not loeal- Lzod to thc adrcnal ncdulla but cxtends to thorc roecptorr Ln thc pcrlphcral cLrculatlon on whlch hlrtanlnc exerto ite actlon (41, p.567) . BLetaml,ne har becn rcportcd by a 22 nlebtr of invertigatorr to lncrcaoe ths pcracablllty of tho captllarieg to the skln anrd mugcular tlcsuca 137t 76). In thc rabbLt and dog, cxtravamtion of, dye has been uaod as a neasurG of lncrcated ceplllary pemcabtltty (41, p.557) . Pyrlberrzaminc hac bGGn relrcrtod to dlmlnl'rh or lnhlblt thc locaU.cad accunulatl,on of dye whlch urually followg intradcmal lnJectLon of hlatamlne (65). Adronolvtl.c Druee DtbGmnlne lr a mmhr of thlr group that has bccn rtudi.od cxtenslvely. Dlbcnanlne wat found to bc a hlghly potent 5-m antagonLaGr on tho Lcolated organr of, rat (utcrur, atmach, colon) and rabbit (ilcun, aorta, htnd Ieg arterlcr) (47, p.75, 271 88t 23, P.315). Atroplne and Atroplne-Li.kc Cmpounds AtropLnc ls reported to have a hlgh dcgrce of bloek- ado agaLnrt S-ltT on the gulnea plg llern (66). Anong the atropLne-llke ccm;rcundr which have been LnvcetJ,Eatcd nonc haa oxlrlbi.tcd thc hlgh dcgrec of potency rcported for atropLne (66). Ermpathctic Aminec IcoproterenoL (lroProPylnorepLnefhrine) Ls rePortad to bc tha mort of,fectl,ve S-ET antagonlrt of the catcchola- nlncr (38r 16). 23 DJ.chloroiroproterenol (DCI) la a selective antagonLat of adrenergJ.c beta-rcceptora, ag classifLcd by Ahlqutct (1, p.595). llhie agent j.e rhem to lnhlbLt the depreeror eff,cets of epJ.neSfirine and leoproterenol and potcntLatee eplnel*rrlne and norepLnephrlne prcssor reapontcr on the blood prGrture 132, p.213), DCI ie a 1rctant antagonist of thc nyocardLal contractlon by therc amfurot, prerwubly W a ccrpctl,tl,ve type of antagonlm for the myocardLal re- eeptom (28, p.l0) . 1[he trrctcntlatlon of norepLnephrine actLon on tlre blood prctturo bry DCI ia boHsved to be re- lated to j.nhlbltl.on of noraplnophrlne uptaka Iry thc tisgue storage rl.toa by thia agcnt (28, p.8). ltlrcellancour JUnGnts Bulbocatrnlnc lltrlr 1r an alkalold f,ound ln thc tubcrr of corrzdalir S. gtructurally lt har tomc rcrsnblancc to apmorphlnc. Petcru wae fLrrt to invcrtl,gatc thc pharmacology of bulbo- capnlnc (59, p.173). !!hc rtudlea on thle alkaloLd have bccn rtlnulatcd becausc of lte ablltty to producc a atatc of plactl.c eutatonla in various anlmal apcclcl. It Lg poctulated that thc bulboeapnine lnducod catatonl.a haa a central hLrtanj.nLc ncehanica (92). lItrtr portulatlon galned romG aupport whcn l,t war rsrrcaled that antlhlsttnlncr aush 24 aa diphcndramlnc antagonl,sod thlr type of catatonLa (99, p.500). It ir also ptcLblc that a dcflclcncy of central norvou! ryrtem rcrotoaln creatcd by bulbocapnlnc cerotonln blocking offect sry be rcrponeJ.blc for the cntatooLe qmdrme (92) . neccntly Lt war rclrcrtcd that butboceprlnc can potentl.ate ame of the actions of hiata- mine (14) . fhtr trrctentLatlon eff,ect lr bclievcd to tro rc- latsd to thc tnhlbttlon of dI''nlne oxj.daao (DAO, hiatanLneae) bnr bulbocapnlnc (13) . further experLucntc rhffod that thc lnhtbl,tory cffcct of bulbocapnlnc on Df,O war dlmLnlrhcd tn tlro prcrcncc of cxcGt! pyrLdoxal phocphat.. lrhlr may tu5l- port thc hl4rcthcrlc that tha lnhibltory action of bulbocap- nLnc on DnO nry bs Lnduccd, at leart ln ;nrt. through Lnteraetl,on wlth DAO eofactor, pyrldoxal phoeXihate (13) . trcorc and Sogclberg havc rclnrtcd an avoragc decrcare of, 37 pcreent in arterhl and 5O perccnt ln the venour pro.rurG wtthin 30 ninutcr aftcr lnJection of doror of bulbocegrLnc renglng frm 30 to 6O ng,ztg (39) . Reccntly Walargek and Chalman have roportcd a dcprcrsi.on of the usual hypcrtonalve rcrponrG to norcplncphrine and a re- vcnal of tlrc rctponrc to cpLncphrLnc. lfAlr 'adrenergJ.e blocklng' effcct war produeod at dorea of, 3O ngZl SOttE PHAI}{ASIOGICAL, A$PBCTS Of BOIASgIInd IOH Potaralum is tlrc prinarf, intraccllular catLon. llhe potarduo eonccntratlon ln thc cxtracellular tluld ls low (about 4 to 6 il In htrnrn plaua) cmpared to the intra- ccllular fluld. Eowcvcr, excogrl.ve variation in elther dl.rcctj.on Ls crltlcal and ctn caute rerioue dirturbaneGs, 26 GvGn dcath (51, p.88). lNechanlrm of potacriun actLonr ,lftra prJ.nary actLon of potartlun la tlrc maLntenancc of tlre irotonlclty of the cell. Ecif,orGr, lt le alro lnvolved ln nany vl,trl ecllular functlonr. llhe ion ir knarrm to bc errentlal tor nomal cardiac function (19, p.546) . Io othcr organ rotpondr aa dranatleally to altcratlonr t n extraecllular potaulrn lcvcl. An Lrolated heert wlll rtop J.n ryltolc lf lt 1r dcprivod of lrctarLum ln tho pcrfurl-ng fluld (19, p.546) vhllo an lncrcarG of potaetl,um lcncl vlll caur. cardl,ec arrcet Ln dlartolc (19, p.546). Itith a nodcrate Lncrcarc of, about onc to *rc q/Il.ter abovo the uppcr lrn{ts of thc control valucl ttre anplltudo of tlre f vavr wlll lnercalc wlth d.multanGour rlrortcntng of ltr duretLon, latar, thc QRB cmplex nay boconc pro- longcd (18, p.47 t 79). At corccntratlonr of 7.8 to 9 df pcr X,lter the 8-T ecaroent may bagln to tlnlr and contlnuor to drop ar thc potanlun concentration goct up (97) . ![trc p rravG fLrst rldonr and loacr anplltude at conccntretionr of 9-4 to 1l nlt, and dlraplrGars cmpletrly at hlgher co!r- eentrationr. At concentratlone hlgher than 10 nM tlrc O&8 cmplex beemor wlder and thcn progrrGtccs to cmpleta dLr- organLzatlon at hlghcr lcrrolr (97). 'l[}le effoetr of 27 Iopered potareiun lenelr on thc lrritablltty of lcolatcd hcart muscle recenble thore of increaeod potassLun level (93, p.546). Other Lnveatigatorr have rcported that thc arrhl&hniae Ln lcolated, trnrfured rabbit hoartr caulod by eplnephrlnc aro araociated wlth an increased rato of potaesiun losc into tJrc pcrfusion fluld (48). In additl'on, thay f,ound that ttrcre rrrhythmlar can be rovcrrcd by rclatlvcly nt- nuts anountr of lrctrarlum (l1O-220 ug). trt war thcrcforc esrcludcd that potaarhm loer lrm thc nyocardLun nlght be an Inportant factor l.n thc lnttLatton of cardl'ac lrregular- lticr (48). lfhero bevc besr a nunbcr of rtudloa on thc ef,feetr of catcctrolaoinca on thrr dictrlbutlon of, potarclle Ln vitro. (?5, g.28,21 91, p.218). llhG rcsPonsc of a nueclc to epl'- ncphrLnc le accmpantGd b1r changer ln the dLetrLbutLon of potaritu betrvccn the collr and tlrcl.r cnvirotmont. Elirr hea rsportcd on inercased lorr of lrctarllum, rcduction ln ttrc msubrene potcntlal, and lncreaaG in thc frequoncy of rplkc lrctcntl,als ,,n anooth musele rclaxed by eplnophrlnc '(20, p.476). Bulbrlog, on the other hand, found a galn of trrctaarLun, hyperpolarlsation of the menbrane, and a dc- crclrG ln fnqucney of rplkc Potentlrl ln emooth mulelc 28 rcl&rGd by oplncphrLnc 17 , p.278) . In dralct'al nurcle an lner;arc ln tlre f,orce of, contractlon }tr eptnc$hrlnc occurt aLong rLtrh hypcrplarlzation of ttro ncnbranre and a de- croared potaaritm lorc l7 , p.283) . traddcll hae reported cn Lncr@tlo ln the 42r uptakc and potartfuln content of rabbLt aurlcle folloylng epLneph- rLne adnlnietratLon (91, p.219). 'l[lrl'c flnd'lng lndlcated en Lncrcerc ln both thc I'nfltrx and efltrx of poterlun \z eplnephrina and norcplncphrlna (f x lo6 and ?.5 x 105 t't) r hwover, tltc effect on lnflrur raa dightly greater than thrt on oflu:r, and not geint of trptaralum wGrG obconred la trGrted aurielor. 'lllla totrl inercam Ln the lrctarcitun f,luxoe nry be due to two faetortt an i.ncrcered f,lux through the rcsttng ncmbrano and a faltor rato of eontrac- tion durlng treatnent (91, p.219). Eowcvcr, ttrcrs Ll no crrLdencc tlrat nore thfn nomal amounta of lrctaraLun are cxchaugcd at cach boat rrndcr thc lnf,Iuenco of cLttretr aminc. In an offort to locallzc tlre slte of actlon of epl- nephrLne on 5rctacrlrs movcmentl, a nnmbcr of blocklng agcntl, dlelrloroiooprcnallne (1-(3, 4 dtcihlorophonyu -2 J.roprorylanlne cthanol hydrochlorldo) a beta-roeoptor blocking agent, and phenoxybcnzenlna, an alpha-rcecptor 29 blocklng agent, wotro uged 175, p.275). lf,he reeults ehqred that the incrcase in potaeai.trm uptake by eplnephrJ.ne was blocked by dtchloroieoprenaline, Ln conccntratLong which blocked the increage ln force of contraction produced by epinephrl.ne. lfhe increase i.n uptake, horgver, was not blocked tryz phenorrybenzamine, whlch dld not block the in- croaae ln force of contraction produeed by epinephrLne, lfhege obsenatlons may suggcat that the lncreaae ln potaa- elua uptake wal due to beta-receptor occulntl,on 175, p,275) . Further evldsnce of the lnvolvement of, potaceltm wac preoented W Scrtcr gg g!. who have re;rortcd e diroct cor- rclation bctvcen blood prctturc changer and novenent of aodLrn, potlralrn, and water bstuoen the i.ntraccllul.ar and cxtraccllular empartmontc. Adrenorgic blockLng agcatr, auctr aa rcgrltj.nc and benodllne, rr€ rcportcd to block both ttre prcmor ef,f,oct of eirculatory rnlrrer and ttre almlnttrctl.c nerv€ lnpuleer. lfhc cffectivonets of thcgo agenta in abolishl.ng or rcncrgLng thc preaior eff,ecta of cetechola- miner corralates wlth thelr effectivensss in dLnLnishlng thc catloni.c rhlft (69). It is poarlble that tlre ionic rhtft tr playlng a rolo at t primary tourcc of energy for cmtractlon (69) . As a reault of extengLvc rtudier on tho eetLonLc chengrce, Scrtcr pt tl. havo cqrcluded that tthc 30 catochoX.anlnor, tB prersor agGnta, provldta cnGrgy for muacular coatractlon through acccleratlon of cetj.onle ghifts, Illndrance of autorrmlc mo\remontl, by conttralt, eauaes lnralyzing effecta. Glycolycla, ttre rceondarT courcc of anaerobic 6n@r{tr}r, i.s uged to f,urnl.ah the re- qulremcntr of muacular contraetlona, but thLc cource La I1nltsd ar tlre lrynedlate and grcat Lncreace of tlre lacti.c acld ln tho body fluldc pnarmbly haltr thlr proeGro. Eence, tlrc energy derived frm glyeolyalr is not adequatc for mulcular actlvlty aftcr an adrenerglc blockadc" (69). 31 TKPERX}iENTAL PROCBDT'RES AND RESU TS Eealthy mongrel doge of olthcr aex weLghing between 7 and 15 ktlogra^tso and Spraguc-Dawley breed of rate of eithcr eex wel,ghtng bctrrcen 1,75 and 300 grans tf,ere used ln dlf,ferent pharec of the rtudy. A1I dogr, wlth the ex- eeption of thoee whlch verG reaerpLnlzed, t Gre anegthe- tLzcd Lntravenourly wltlr pontobarbltal eodltm, 30 ngft,g. ![hey wsrc ventllated wi.th a Earnrard rctpLrator attached through a traehcal cannula. lfhe volune and rata of venti- latlon wore kept ln adjurtnent to avold improper vcntllatlon. In gcnoral, the anlmalg rcceived300 ml. of aLr pcr stroke at about l.O rtrokes per mLnuto. Blood prerlure lraE re- corded frm a trrclyethylono cathotcr Inserted ln thc carotid artery and corurceted to a Strathan or $anborn tranlduccr. Rccordlngt rGre rnade by ncanr of, a Sanborn t{odcl 150 ampllf,ler ayrtem or a Grara Inrtrumcnt Model 5 trrclygraph. Contractl,le force of the heart wat mGaEured Iy mcanr of a Walton-Brody ctraln gauge arch cuturcd to the rlght vcntrlcle through a rtght thoracotmy (93, p.349). lfhe gtral,n gauge gl.ver ereentially a llnear deflectlon on c rceordcr under the condltione of ule. Electrocardlo- gralfiic EGarurencnts wcrc alco uade ualng lead fI. 32 In placlng tlrc rtraln gaugo on the ventrLclc, a rllt war nedc ln thc perleardium to oxtrlose the nryocardl,rn. Suturce wcrG plaeed decp in tho ventrlcular nurclc wlth a non-cuttlng edgc, half ci,relc ncedlo. [umber 8 cotton thread wal ured to tlc thc fcot of thc arch flrnly on the myocardlrra. ![hc mulcle aegmcnt undor the arch rrae rtrctehcd to about 5O pcrccnt of ltr norrnal dlartollc lcngth to pro- vlde ruLtablc contractLon (93, p.349) . ![hG arch war attaehcd to an anpllfler url,t of the Grasr Inetnuent or the Sanborn r€cordcr. llhr sxtcrnal Jugular vein ua. eannuletcd for adnlnlr- tratlon of drugc, whieh wcrG werlrcd tn wlth 2 to 5 nl. of gal.lnc. All anlncs uecd l,n thlr atudy wcrG nadc up ln rtoek rolutLonr urlng a prarGnrativc solutLon of 0.1 per- cqnt rodl,un blculfltc and 0.I pcrccnt chlorbutanol ae dllucnt. All othar natarLalc urcd wetre nade up in thc rogular ray wlth water or phyrt ologlcal rallnc at thc timc of ute. AII valuGa arG rc;rcrtcd aa averagc rGtlronscs with calculated Standard Brrotrg. A gerlcg of cxpcrlnente were declgned to providc ao ncarly ar poralblc a defLnlte cqrclutLon ar to tlrc neehan- Lcm of cffecta on the blood prGuuro and the eontraetllo forec of thc hcart b,y 5-m. Allo, lt uae ftrlt to bs urcf,ul 33 to otudy bulbocapnine in regard to e Souro of the drugs to be studied and alL of thoge to be ured for purlrcrer of cmparJ.con rrerc given to expcrl.- mental aninnlr to detennine control levels of, rGapontc. |fheae w€re rnalnly the determlnation of different levela of reaponae to 5-Xtf, and of ftxcd docea of, aorno of the catcchol- amines on the blood preisure and the contractlle force of the hoart. SolutLong of 5-IIT were rnade fron a atock golu- tlon ln preeenratlve. 34 It was desirable to dctemlne doee rcapotra€ curvcs for 5-$[ urlng thc sralleet doca producing a raprodueLbls re- rponre and the largcot empatiblc wl.th phyrlologLcal hmcortasLa of thc anirual, with two other dore levcls oqually alnced botrccn thclc. ,|[hc dorag. rangG uegd was 5 ug/t.g, 10 ugft,g, 15 ugy' l;,, and 20 a9ft9, rcrlnetlvcly. Doro rGapoasc curryGr wGtrG conltructcd frm tbc avorege rGalronror of tlrc above and urcd ar controlr for ccnlnrlron wlth dorc rcrpontG valucl obtalnod ln letcr cx;rrLmontl. Control rerlron..! yGro dctctmLuod for opLntplrrine, noreplneplrrLne, and lroprotorcnol at a docc of 1 rog/t.g, rerpcctlvely. EtlrylnorcplnclftrLnc rcrpcrtGt ycrc obtainod at a lcno1 of 50 ugzt;g. EBl,ncSihrlnc aad norcpLnrl*rrine arc conrldered ar phyriologica} prGtror agontr and arc urcd ar rtandrrdt of cmlrarLron for all, drugr producing a tinllar ty5rc of roqrouo. Iroprotrronol and cthylnorcplnotrfirLne were urcd ln the rtudy to ald ta pronlng or dLrpronlng the bcta-adrcncrgle blocktng actLvlty of 5-E by the mstlrod ruggorted by Ahlqulrt and ottrsrr ln vhXdt rn lnhlbltLon of the Lroproternnol doprcuor cffect and produetlon of an BtE rcvorral arc cont!.dcred ar evidencc of, n bcta-tdrcncr- glc blodrado (40) . IAIIA I and Flgure 2 tlluatrato tho rorponror to 35 ${.OT {J .[ l'l @ N (o $ lr] tn @ OX d Ft F{ Fl !!l t o k (,r(\lo0(\l .\lll0tt aataa taa ot r'l1oOrtt FF$. our F{ OE +l e.El{ +l +l +l +l +l +l +l o\ornoo N({U'I tr L ataaa aaa o d o(n('lroN F{fAO df (rtm utE o F{ atl til Uf Hfi T tl Erp l-l IA orto(0o@ rnoo xH I aaaaa aai U ()u1O{!t 6N$ dA .r.l rl F{ d F{ElEl ErO o +l +l +l +l +l +l +l +l gE tl(\$(,to()9(o Hg aaroaaal HN u OGIOI0F$F{N il Fllftllnltl{A H NO 5 BE ,lNototolto\o o dnn hu a t{ Ogi .rlF{tfurFOIu'lUattra.. ('I o 6[. E +t +t +r +t +t +t +l +l bm If @ o m o to to o o ,! ,-I +laE ..atal. t 8H g(,ltoolnooa o UIU f,rmlopltN (r) t Hfi }I'l3. t oo to ln F r\ (,l .0 F FO trU (r(, . t . . I t at E{ N Nan a alt tn rl tl tn tn o Ig +r +t +t +t +t +l +l +l U 6o F{ N A F o tn ON . . o . . . aa Ur.l-.'{ (D m O F d F OF It*r F{ fl) t, |n ln l,n lnln T oI a ,ig & o ! tn tn U| d tr 9\ o H $ $ $ f;, E, E, e: o { EN E' It ' o "Et Et E( H 3 rn I I F Ed 6$ ii ig o $+Ef;qg:B:$:Bf n tnlntnrnEl-HrfB t M. P. RESPONSE 36 mm Hg 7O C. F. RESPONSE O----O Meon Pressure Res,ponse H Controclile Force Response f-''-'-t--, I LOG DOSE zrg/Rs / Figure 2. CONTROL RESPONSES OF s-HT ON CONTRACTILE rORCE AIID BIOOD PRESSURE. 37 different doses of 5-I1T and the controL responses to epi- nephrine, norepj.nephrine, isoproterenol, and ethylnorepi- nephrine to the bLood preEsure and the contractile force, It strould be noted ttrat all but the smalleet dose of 5-lIT cauged a definite preasor response. Ihe ottrer drugs shorred the typlcal rea;ronaes deccrlbed in the literature (89). El(PERIl,tlilm,AIr CROUP HO. I An att@pt wac made to detemine the part the adrenal uedulla playcd in the preror responrca producGd blr S-IIlf . lfherefore, I dogs vare adrenalestmized and 5-Ilf rerponscr werG recorded before and af,ter adrenalectmry. 'l[he reaults, aa reported ln TABI,E II and Flgurec3 and 4, c]row gubstantial decreage in the s-Hf praaaor retponce. Eclrrever, a eorBletc tnhlbttlon of the presgor action naa not gcen ln any of the experinents. Thls initj,ated ttre thought tlrat the prearor ef,{eEt of, S-Ilf that porrlcta following adrenalec- tmy could be the regult of rolease of transurLtter oub- rtancea f,rm the adrenergic nerye endinge. To evaluate thls portulatlon, an agent kncnrn to de- plete tha transoitter eubotanceo aa welL as the adrenal Itoroc, and otherr knonm to Eelectlvely block the releasc of, the treamitter eubstancco of the adrenergic nernre .., o tro tr o t 38 'q .;i it .cso i: sf{J *] '.1 {J if'.{ +J i g ;- +,A +ro O -tE"'l EIEIESIE ul El tr Ho E.t , fB Ht Eu EH fiI E utI ,* oi o+, n !n $ .n q o f,l EEdS d t ttn q @ I $ t''l q a () 2rnF{ot &o 6l EU, Fl Fl Fl flE +l +l +t +l +l Ag tt ro o o r{O o $ aa a I atsataa ln0 o ln (\t rDx RS il FlI E E o ('l0(,lr0 r{ Hul f.a.. a r{ El (rFt!Ool ln fr EID F{E-{btr{A g; +l +l +l +l +l HEdu oE o o o o N() o Hg aa a qlt@tto|h.!.. to0 o !. Nlolft: (\ co A()F,ltnN €Sa -'{[email protected].. FIU! vl F{ ,df,.a +l iT +t +r +r +r ete He :E oo N o rr o o o 3.gI da.rtaNoc0o gg,8 g (\ tl rt Cl ({i d d n0-r{ H ro sr SndP H lOrt F{ H (r(, N d ; ,'B'# dk d +l BrE I $!.o lt{ +l +l got,fo F ,l o o 5EioJ. En ;o OO r ii i r . * . O -Ud UF{ O Ul rf rn c HOfr, t{ ..{ O ro 6r' r iRr, d g.iof H tj tr Efl8u9 E .EI h rfii! Dr trr 5 xt hrt, -Y,AAYl E EB 8i<. sg,flg3 \ rl tnN b E lavJ(Y,{o f,45ifl. +r e o\ o\ .tr t t." t6g a gui trur +, E ,e ,er, o 4e -AE O \ fil filotr EiF{+r+reo tn C trFl'.{ flHeEE 4- 0C) 0C) d E O O d tf,=O O r aa >,1 UF{ OFl X H r{"r g !!r, E r i -r(\l I t,l il,A s 3 H Ef I EEt rii-- 180 I20 120 140 80 80 100 40 CF CF coti[TRoL ADRENALEEH}{Y & ADRE}IAI,ECTOI{Y GUAIIETHIDIIIE 1O ngTl (, Figure 3. Courtrnrative Responses of 5-ET, 20 vgy'rg, on the \o Blood Pressure After Dfodifying Drugs and Procedures G' loo - (l) Control E (2) Adrenolectomy E (3) Dc I lrj (4) 3T' Heromelhonium z (5) N icoline o (6) oo- Adrenolectomy a Gocoine trl ( 7) Adrenolectomy a Guoethidinc E, lrl G, g,f U' lrl E, o. 4 z lrl = Flgrur.e 4. COII{PARAITVE RESPONSES OF 5-IIT, 20 ug/lr..g, ON TEE BIOOD pRESSt RE AflTER IIODIEYTNG PROCEDURES. or 41 taralnalr, worG ut3d. Rererplnc, ar prcvloual.y atatcd, 1r knqrn to depleto tlrc catecholard.ne and S-llf ttorcg. lfhlr agcnt ree glvcn lntravenoudy 0.I rng/cg dat ly on tvo coD- recutlve dayl. On tlre thlrd day the aniual wts clrefulLy rnorthetlzcd with pentobarbJ.tal oodi.un Lntravenouely, and tupplcnontcd with goall ertountr during the oryerlmentE to natntaln a rurglcal pJ.ena of anesthesia. !!}tc anfunalc uGrc prcpared for recordlag and ttre ugual obeor$ati.onl. 'll'lro data ob,talned f,rom thir study alc presented ln TAALE III tnd Flgura 5. llhe renrltr rhorr thlt rererplnc dlnin- irhcd the actLvtty of 5-m in eadr area rtudLed, indicatlng thrt 5-m dcpendg on catecholaminc rclaarc for ltr actlon. Grnnethldlnc, an agent wlt} lnhlbltory actlo on ttre rahaee of tlra tranruitter nubrtanccs frm the nernro tenni- nnll, war gLven lntravenoualy, lo ng7'kg, to thrce adrenalcc- tmlzed dogl. Aftor 30 mlnuter, 5-m dorea uTGrt rdnLnir tcrod and ths uatral rGslronaGa w6re rceordcd. Gumcthj.dlne empletely lnhlblted the prertor roaponre of 5-8ts on the blood pr€ruure of tbc tcrt anLnalt (soe IABLE II and fig- uror 3 and 4). llhe contractlle force eoetpon€nt of 5-8! war only partially blcckcd, providLng avldcnec tlrat thla agcnt mry be acting on rpcclal rcccptor ritac ln thc Eyo- cardJ,rn indepcndcnt of, all catecholamlnc rocoptort. GI $ sru! uilr cszD[I.rEssrx l[I &g-s ro ggsNoir8gS mm8slrud ooclE cm{ gSEor sIIIfxtE&Noc xE[ rlf gfEtl,tr raauodser eSEreAY * L 9'4T 7 z'gz B'9T T z'sz g'oz I z'sz 6'0r f e'er bn/ba oz &r-g L ?'or T o'oz ?'g T o'?z v'zl T o'9T 6'z T €'BT 6:4,/bn gr [g-g L z'g T 0'6 o'9 T ?'rr g'E T B's r'[r T o'gT btv/bn oT r,E-E L ?'t T B'9 o'T T o'g 9't T 9'g s'9 T o'Er bry/6n g e,E-g 'aXd:cg 5g w 6g um 69 w 6ecro3l eTTl lua6V Jo 'of, ;orrlaaard uBelf pc11o1etrg roTTolBrTC -cerluoC N O----O M. P. GOntrOl G--+M. P Rcserpinized 5 6 C't Rescrpinized fi, lrJa E 506 E4 (H o. C. F. Control a trl lrj az ot 8e 40u u, G lrJ r-'-''--, &, I tro lrl CO-|z I tr, 3 lt at, 30.J a Fo UJ Ez,.4 G /t Fz z I 208 u, I Err6 l.8 --rJnk' LoG DosE n/ i Flgure 5. THE CONTRACTIITE FORCE AND fHE BIOOD PRESSURE RESPONSES OF s-HT IU RESERPINIZED A}II!,TAI,S 44 Cocalne, l0 to 15 W/t.g, har an actlon eLnllar to gurnet*r{dlne 1$ inhlbltlng t}rr prearor aetLon of 5-E on the blood prGmurG of adrqralcetmlaed dogr. Berultl arc rhcrrrn d.n IABI& II and flgure 4. EXPBRII&|8,AIr G8OUP SO. II t.hc qmtrrthoedronal actLvtty of hlrt.'nlnc har boon portulrtcd er a poulblo nechanLm for tha prorlor actlvlty of 5-B (92). A prcraor ro!tronrc for hlrterntnc har bcan relrcrted Ln a nnmbor of rlrcler (80, p.349, 8). In the prelLmLnary rtudler ln thlr LnvoatJ.gatiorr, hcrrcrror, hlrta- mLnc fallcd to produec a proslor off,ect ln thc doge at dl.ffcrcnt dorage lovclr. lfhcrcforc, i.t rcmed doalrablc to dctcrnl.no the prGr.trco or lack of a rclatlonrhlp be- trroon hlrtanlno and 5-&f. A nunbor of oxporincntr rerG pcrformed urJ.ng s-ltT af,tor roEG blocklng agcntl. |lhe ob- eenrcd rerulta wlth S-Ef wGrG copred wltb thoro r;1rcrtad tryr others for hlrtanlne. Auong thc blocklag agonts urod ycrc hcxanethonlum, nlcotlnc, and plzribcnaami.nc. Eexamcthonitn ehlorl,de, a c@petltlve ganEllonlc blocker, war glven lntravcnoualy, lO rag/1tg. Aftrr 3O nLnutcr, nrbrequent doroe of 5-ET produccd prGlror rc- sponr€l which were narkedly potontlatod (eeo IABLES XI and ilI and llgurer 4, 6, and 7). It lr alro of, intorert to 45 tfl. oo tttt ttit {J ,tttt tlrt rP1 (rrtf srf @Fu1 rn tSt0rl !rHox t o t$tlO NO\oO GlN$o t{ taoaaaaaaraa a ONOt! rnNF{ln mo\nlC) C F{ F{ r.{ F{ Fl F{ r.{ F{ r{ N otroEn +l+l+l+l +l+l+l+l +l+l+l+l frEft oo$O cl(\aNrf to()!fc0 !l otaroataaaaa H a oooo fqForo n(:)oo u d IoFo!O fq|,ltf{ rn@FO D o F{ t{ u, T ul H fr to{\0 to006l N(\r@o e. t aarrlaaaaara u o(\aNo or@frrlfl F{o(\lro A r{ Ur Ft Fl Fl r{ r{ Fl F{ Fl F{ F{tr o o +l+l+l+l +f+l+l+l +l+l+l+l g +rE ooo.Yt oNo{ ()ooo El aataataaoaaa o (,llE ()F{{(It TONNO OC)OtI E1 FOO fvrOtn$ !nG0r\O EU Fld r{ Htr uafr t tloNN N(0O(D {N()O U atalaaaaaaoa gB .r{ o8ln.a Fro0u1 ()(,rGlN B H F{otr Ur F{ ,{ rl Fl r.l Fl l.l N HT {, +l+l+l+l IlH HH +l+l+l+l +l+l+l+l d E{A EE ooN{ tr\o$N N()6tN .ia atraaaaaa.ta H o OOI(I|() ()Ft@Fl mOnF E8 ln€@ol mtn{tn tn@\ool [.r d OHtr f.l O\gOF NGINF roorF{O UEr {3 aaaaaaaaaaat 1, {FttFl (rlrI(t|O $tfOlr0 tr Ut,to Flr{N l\lGlr{l.{ F.lFl (\l ah o tO ol,l 4, tH +l+l+l+l +l+l+l+f +l+l+l+l gH c OtIO(> r\()(fO ()O()O +rr(l oo atraaalarala Ur,{ tn(\tvtto FIF{N$ OF{to\g 6n s{ tl\OOO mFrfO t\r{NN R tRr, A FIF{F{ 6Scul tro Fl OF{ C ur tn tn En trr tD tn En Er do .,x J( r( t.E!Fl o+Jx o+,ft o+rx't A CE,A Hr{ O k-{ h-{ O tr t Fl !t A t A !S O tt Elr -la H 5- HT Response E Control E lrl zo o Response o- s-HT a After Hexomethonium trJ G, trJ o:-----€ G f s-HT Response ct Af ler PBZ U' lrj E o- G-:-+ z s-HT Response After Hexomethonium A trl Pgz = 5tot520 LOG DOSE -t$/ ks Figure 6. THE BIOOD PRESSURE RSSPONSE OF 5-IIT AETEIR rI{ODITrI}IG DRUGS (rtF H t40 s-HT Response lrj Control az rzo of lrJ o----o G. 5- HT Response too After PBZ olrJ G. e80 H trl s-HT Response Jso Hexomethonium F () Fqo e--+ F 5-HT Response oz Af ter Hexomethonium ozo A PBZ ng LoG DosE oy' rn Figure 7. TT{E COIIITRACTILE FORCE RESPOIISE OF 5.IIT AIryT'ER II{ODIFTING \tr 48 not6 tlat hexalrctlronium chloride hae been found to Lncrease the preaagr reaponse of histanLne Ln eats without alterJ.ng tlrc characterl.stLe of the rcapoaor ( ef I . Elcotlne hEs a biSihaelc blocking actlon consLrting of an lnitial phaac of, delrclarLzatlon of thc gangllon colIs, tollowed by a aubtequent phaoo of conpetltlve block r{m{Iar to tlrat producad lpr hexanethonirsr (58. p.50). slcotlnc wal uscd ln rueh a way to produco an lnitLal phace of gang- lionlc blockade b1' depolarlaltlon, nl'eotine bcing lnJceted In lneraatlng amorrnts of 0.5, l, 2, 4, and l,o W/lr,g.- 16- rpcctively. lfhe last doce lfat r@pGatcd untll t}cre wag no longcr a prctsor reslronse tcen (81) " A total of, 10 to 2A mgt]xg wBE roquired to lnducc cuch a ganglionic blockadc. Subaoquernt lnjectlonc of S-ET Eholwed no aPpreel.able change qnrer the control valuee, altlrough thc preeaor reslronEe to hLrtamlne has been reportcd b1' otlrers to be aboll'gh€d aftcr a c{milar treatnent in cats (81). ftrirty mj.nutcE later an j.dcntical rerles of nicotlne lnJcctlong wGrc made to pro- duce t}c second phaae of nicotlne action, a copctltl've ganqrllonj.c blocikade (81) . Eubaoquent lnjection of 5-IIT cauted a proroor rasponne rrhlclr osceeded the eontrol valum obtaLnod carller, but these were not rlgnif,lcant (cee 1IABLE II and Figure 4) . fn afulLlar dxPerlmenta Ln cete 49 roported by otlrere, the olftctr of, hlatanlnc have becn ehq:r to be poteatlated by the recond phare of nieotlne blockade (at1 . Tripelcnnanine (pyrlbcnrulnc, PE), an antllrLetulnc, wac given i.ntravooucly, 10 r,q,frg, about 30 to 40 nlnuter prlor to adnlnirtration of 5-ET to tert furthcr tho poeri.- btltty of lntcraction of S-ffi and hi.atanlnc. lfhc rcrperoco of 5-Ittr on contractllo f,orce and blood PrGaruro vGrG potcn- tlatad. ftric potentl,atlsr wat llorc rnridont ln lorrer 5-m doaor, 5 ugt}.g and 10 ag/t.g, than hlgher doloe, and reoncd to bG tl,nc dcXrndant. llhe reeulte are reported In TAAI.B I\I and ligurco 6 and 7. In tho follortng eperincntr PEE, 1.0 ng,ztg, rnr gLven followLng hexanetlronlum, 10 ng/(g, in ordcr to rhov a pomlble furttrer lrctontiatlon of, 5-I1f,. RG- rlronscr folloryLng thcra agcntr a3 relrorted in TABIA fV and Plgurer 5 and 7 arc greatly potentlatcd. UPEmIf@fT,AIr CBOUP UO. III 'iIhc effcctr of varlour blockiag agentc' on thc presaor roaponror and contractilc force of S-HT rcrc rtudied to furtbcr clucLdate itc actlon. Dq[, a bctr blocking agent by the tertinologpr of, Nrlqulrt (1, p.595), wet glven both try tnfurlon, LO agl\g, crvor a lrrLod of 45 ninutct, tnd \z alnglc tnJcctlon. trn 50 both carcr thc contrectl,lc f,orco rcllronte of 5-8ts wat cm- pletoly abollahcd. Eotrcvcr, DCI produced only a partlal inhlbttlon of ths blood prot.ure rclponte of, 5-8tr (roe IABIrE II and FLgurc 4) . Vagotory wat parformcd ln a nunbcr of anLnelr hlt faLled to rhw any effectr on the 5-B aetlons. In three anLnal: progrngllonLc almtrnthetlc blockade war produccd. ![tre blockLng proccdure wat elmLlar to that delcrlbcd by Brewrter g! g. (5, p.38). A lumbar lemLnectooy wal por- formod, thrcc po1ycthylcnc cathetort wcro Lnrartcd lnto the cpldural .pac6 go that thelr tipt lay at about thc leval of CZ (ecryl.cal) , !!3 (thoracLc) , and 91 (sacral) vsrtebrae. Approa TXPERU{IUT,AL GrcUP HO. rv iltrla group of experLmcntr vas derlgned to walunta the lntrj,nslc actl,on of bulbocapnJ,nc on tlre blood prellure, 51, eontractlle force, and eloctrocardlographLc (EKC) trG- aponaea. lfhree doee levelg of bu].bocapnLne wGre used, 10 ngltg, 25 mgftg, and 5O ng/rg. A narkcd dore dcpondont dcprccsion hraE observed in both csrtrastlle f,orce and blood prerrure f,ollqrlng an lnJectlon of bulbocatrrrlna. lIhe EKG changea wcro rnarked at tLmee and rerelnbled those of potaaciur toxtcLty. 'ltAELE V Ll}ustratcs the obcewed retPon6cS. In an attempt to find the reason for the ehanger ob- servod ln tlre B(G, the potaraltm content of thc bLood rerun wag deternLned. Sanplce of blood were drawrr Gvery ten mlnutcr frqtr the tlme of inJection of bu}bocapnino untll tJrc cnd of the e:qrcriment. lfhe oamplec wcre contri- fuged, the cerum rearorred and properly diluted, and the potaarl-ur content l.n u WL nas detemLned ln a BGclcman 121 flane photmctor. l[hc aanrn potaoelum lcvel declincd pro- grerrlvely follwlng an LnJcctLon of 50 mg/kg bulbocapnJ.nc, havlng a aharp dJ.p about 40 to 50 minutes after adminLetra- tloa and then rlelng elorly (sec rAaLE vx (A) and Flgurc 8) . Xn an attenpt to deteraLne whether the f,al} ln genrm potadrm would reclprocate vlth a rl.cc ln heart mucclc potue!.r.rm, the ani.ualr wGro gacrl.fl-ced follrylng tlre expari- mentc and t$rce camplea of the left ventrlcular chambsr of 52 tHr o! I {J i rQ rt t\ tf F EHox t o Ll.n Ft r{ (\l ,. a a a Au') (n $ (a oEn rl otr ".1 (J H+l +l +l * olE +l o N o (\l t! Er trr O I t dtn {n o| o OFI cl r.{ !n H tl I I I H oE{ fi (n n F{ F{ Fl a t I a tr m F{ fn nl F{ I(, I +{b +l +l +l +l haH F{E of, o () c) N o P a a a I HUt BE F{ o ,.{ (\a nrA >t Fl 6t ol ut } 6 I I I I HH s to' ln @ N ln tr UEI t t a a a U F { n ln n .i.l F{ Ff tn tgDE OE +l +l +l +l n *, o OE o \o N o hra dE a a a a O't .r{ o F [r- () a N N Fl u1 T{U H I I I I OH ch F. fFl io lo F{ o(a &l lO a a a ou o' o $ 6 -l&4JCr U fl, t{ Fl (,H ko Er rH ut rH ET {JA +l +l +l +l trO L OH oo o ul o ln F{Et d U-{ . a I a Og E dro rft o N h'rl A }( *.1 N ftc H I I do oooH lt, ctn c uio o c.Cl 3.t EE&il 6 o$B o o u't5 oa ao trd c t{C r{ t'r trt .'a ElO .rl Ul (,i, -{ OY t Et E( aa* Et bF{ o O d tn d a,i 6lr^ UEdur l{orl 8 8o g8t r.{F{T: F{GlT: F{T$$ Ht Filll uac , '(QAI ann m tt 53 Gach hoart welghing about onG gran wcr6 rmovod, fincly hmogcnigGd and d,lluted to tho propcr eonccntration urlng dslonked vatcr. lftre ranpler werc analyzed for potari.tm content ud.ng the came ncthod ar for the tcrun. ![he po- tarclun eontent le rcported tn fAtLE vI (Bl ln ng/lO0 granr of wct tl.llue. Flvc normll, healthy dogrr, vlthout prcrrLoue trcatment, warG ncrlflced and hca,rt tl.lauc Hnplee v€rG troatod as aborrc arrd utcd as controll. lfttc rcrults lGGn Ln EABLE VI (B) etrw a gain of lrctaraltrn by thc hcert'r lcft vsntrlcular murclc aftcr treatmant wl.th bulbocapnl,no. .iftrc prellnLnary ctudi.ca ehowcd that aftcr bulbocaSnlne the anlnal'c bcctnc "scnritivc" to rubrequcnt dorcr of hlrtrntnc. In four anLuale lntravcnoua lnJcction of, O,27 wg/kg of hlatanlno droppcd both contractLlo force and blood prorcurG to zoro and klllcd thc anLuala. lfhe teso doror of hlstamine, end enen hlgher docel, wGra wcll toleratcd whon anlnals had not rccelved Inrlbocapnl.ne. El(PEArt{InrrAL CrcUp rc. V llhcrs cxperlncntr werc carlod out to erraltrate tlre blocldng cf,fcct of, bulbocaprlno at differcnt dorage lcvell. Eulbocapnine yar glven ln threc dotea, 50 mg7tg, 25 W1ft9, and lo r.gftg, to produco nj.nimum and naxl,mun ncrrurablo go88x& u\lrlncnl,[Nll/\ &agT wI(IurTCOm gH,f do Nor&vu,trlucflq? Hnrsw&oa $r ggommc (E) ra trrgs& l'?z + ['67 E'L + LLE g8? 7Ve g0? ?7t OZ,E 80? 9TE 6Le e?s V?E sTErrTrrB pelrer1 euludecoqlng sTrrrruE xorxuoS ensBT& ur6 ?OU tro OOT/bw TeAaT +X 6ry/6w og :ruxNdnDffimg ug,rdv glrr& Efni gomtgc .EMIcugd gcvugAv qNt !firrss\{,lodl }tn$ts t&rto8av (Y) IA f,Igv.f, O'LE 6r' + 9l'3, 0f 'r 06'T O'Z ?'Z 8'Z 0g 5'0? Er' + lo'z 89'T 06'T 99'r T'Z 9'Z 0g 9'?g 0T' + vz'z 98'T v'z sg'z ?'z Z.Z O? g'82 ET' + 9V'Z 96'T L'Z l'C 9'Z 9'Z 0g rTZ ZT. + aL'z Lg'z g'z 6'z gv'c T'E OZ, t'rT LT' + gT'E 80'g 9'Z T't 6'Z 9'€ 0r 0'0 4T' + E?'€ 7'€ e't g?'E z'e r't 0 Torluocubry a6e:eag S V E ?, T tglnuTu e6uertr;l S fpg n uoTlErxuacuoc unlsselod Er.reg uT eurf,E 39 lrl (9z ().L oz F E, Fz lrJ oz ()o )g T IME IN MINUTES porAssruu AflrER BULBoCAPNT}rE 50 mg/kq Figure 8. CEANGES rlr coNcENTRAfroN oF sERu{ ul (-rl 56 rGrlronsos. ![tro doser of bulbocapnlne wcre follored ]y lnJoctlons of S-Elf. A nunber of catceholani.ncs rore glvan after 50 mgt1r,g bulbocapnl.no to d,etemlne thc degree and eclectlvlty of thc blockadc. Anong therc rcre cplneSfrrlne, 1 ug/ B'r ; g'or 9't T u 'GT g'g T z'z g'9 T 6'62 ba/bn 1 eu1.:q{aulderog 8.2 T Z.ET 9'E T, ?.TT 8'Z T ?'g s'r T z' Lz, b>4r/bn T fouareXordorf g'€ r z'ET o'g ; c,'EZ, U'g T Z' L- o'? T g'gz bq/ba 1 eulrqdauldg s' T B'9- B' T o'g- 9' T v'c- T't F g'Tr- 6>4r/6a oe fiE-s 9' T o'9- L' F o'9- 9' T o'9- T'? i L'g- 61/6n Sf &E-E s' T g'E- B' T o'?- g' T g'z- ?'€ E €'g- 6a/ba of rtr-g L g' T r'g g' T E'g g'g F g' E- r', T 6'?- 6:1,/6n S eg-S 'cldr(g ftrw 5g@ 6gE jaoro] eTTl lue6V Iio 'ofi[ lern3aerd uran *cTTole.f,s loTrolaETg -cErluoc x (r) s-HT 5se/ke (a s-HT lo te /ns (3) s-HT ls tts/rg (4) s-HT ?:o,cts/ks GD48 (5) Epinephrine tag/kg (6) E lsoproterenol t A/\e E4 I7) Norepinephrine t ttg/Ug ' trJ (e) ENE . 1o4s/rs a (9) Kcr to ms/r oz 32 ao- lrl E, 24 lrl G, f-] conirol f a r6 a Zme Arter sons/xs trJ E, bulbocopnine o- I z trJ o' = -8 Figure 9. INIIIBIMON OF BIOOD PRESSI'RE RESPONSES OF EX(PERTMBITAIJ AI.TER BI,LBOCAPI\ENE 50 mg/Kg ul X v"lo"" @ (e) ( r) s-HT sttg/rg (8) (2)s-nr Pa/ks a (3) s-HT ts,us/ks lrl U'z 50 (4) s-HT Z6,ttgle (5) o-o Epinephrine tug/kg a (6) lrJ 40 lsoproierenol ltg/kg (r (7} Norepinephrine Ui/ kg trJ ENE. soaE! rs o !9J 30 (e) KCf to ms/ k Eo TL lrl 20 J F l-1 Gontrol o to E, F ru After sons/ rs z bulbocopnine o o ag risrure ro. rNlrrBrrroN oF comtRAerrr,E FoRcE REspoNsEs oF THE EX(PERTUBITAL DRUGS AFTER BULBOCAP\IIITE 5A mglkg Ul Xv"ro"s exeeed \o a tl{ o+,6 60 .O. ttrltt{' tftl$$ sl'ss ssg!t OX EFI $ooo oo\oo o000 to\o@o r{LnCnrf dr{r-sf @o\r{6 tf,}tnF(\ I aaaoaaataaaaaQaa otrctn mmmN FIF{ \O Fl\O f- k +l+l+l+l +l+l+l{-l +l+l+l+l +l+l+l-Fl AE oooN rl€N!n oo\0N oooo it aataaaaaaaaataaa do \oot()o lnor({ttn $q\0F{ lnolol\o Ol{ FIF{l-l FlFl(\lN Fl FIF{ Ato rtrt trtt oOtoO\D CnF{F{O OFI()$ otrnOto I oaaaaaaaaatta.aa a U F{Ft$rvl FlFl\O r{F{1O Flfrf o ..{ tn H FIE +l+l+l+l +l+l+l+l Fl o +l+l+l+l +l+l+l+l H IE F{ONF{ ril\oGl(} (}OOC) $()N$ OH DE iaaaraataataaaao roGltO0 t0orU)@ toN\oO 6Ot\O Htr ra rl F{F{6IN Fl l.{F{Fl EI E! I I I I I I lr HA 4 t oooo o@oo oooo ocl(\aN zao8 (J ()Ulrnd O!tFlqil 6!ilr{rt @f-f-rn .Fl aaoattatlaaaa.aa H (a}I Fl ti l.{$ lilF{tl9 OEUr NGINN $ H BB r, +l+l+f+l +l+l+l+l +l+l+l+l +l+l+l+l - ox EE qocrwt oro\oo 8@oo ooo.\l HEI .r{ taaataaatataaaaa !.1 O o oNc)(\l \oolg}N trItoo ooc0m 6 Aq Fl Fl l.{ F{ r.{ r{ Fl (\l r.l Ft ( HH lltltttt E{ }lUI HOha i U)()Ful mficlF FIor(nO FIo.|(ar- AA. ataartaaaaaaaaar uoro .nrnro{ ().nNQ @rilt@r- F{{Ntrt sH dt{ r.l F{ Fl Fl Fl l.O F. +, lt{ +l+l+l+l +l+l+l+l +l+l+l+l +l+l+l+l oH ooc \ot\roo l,n0\oo cloFt\ tn('}oln HI U.r aataaaaaaaaraaaa ('Ic0()FI Otn {{ toIOOc) q$t?tntoOo\$$ OOo\r\ H Iq *r t FIF{ Atttt F{ Fttf slO hohEr EI tntntn tntnut utotn tntDtn H E{ 8o itstm55, itttvrrra it*t$rru i*tturr,, 5)AAAolno otno olno oroo +, rnFlFlN rrtFlrlN rf1Ftr{N lnF{Flol a 6 $ HHEH HHHft HHHH EEHH o 4tlrrrotornlrl Lnln!nlnlttrrltttttt tninull.n |J.lto|ou') m & d E o o lrs o, o a uo o *rC d C T{ JdC t{ c{{ -{trdA r{ .1 tr \"r oc osc o tr c o E AI,I EnbCI{tr qO ,qU1Elain tt *J dx "q +, t( {tt L d (, u\ o\o o\ h o OUi r EXPEruUENTAL GROT'P NO. VI In ttris group, the animala were pretreatcd vLt.tt bulbo- capnine to teet t}e poeeibtltty that thlc agent may be in- duclng lta effect by releasing s-Ef or catecholerninee centrally, perLpherally, or bottr. Bulbocapnlnc waa adnln- igtered intramuccularl.y in a doeage of 25 rlr,4r;g daily f,or f,ive days. On the eixth day the anLrna,lc wGrG anerthetl,zed and prepared for recordlng blood prcsaur€ and contractilc f,orc@. Subaequent dorea of 5-IIf producod subrtantial re- aulta. 'iIhe action of s-Im on the blood prersure and con- traettle f,orce 1o strongly potentiated try pretreatment of the anlmal with buLbocapnJ.ne ( cee TABLE IX and Figure lU . A later doaage ot 25 Wt1r,.g or 50 mg/kg of bulbocatrnLne, given attor ttre aborre portlon of ttre expcrlncnt, ertablkhed a cmplete inhtbitlon of thc preasor raapontos of, 5-lll. EI(PERIT@TEAI, GNOUP XO. VII llhc rcrulto gained in cxperlnenta with bulbocepnLn- Laed aninalr indicatod ttre poraibiJ.tty that it night bc depleting the ccntral ar well ar the perlpheral. 5-Im rtorG.. If tftlr wGrc truc lt nl,grht bc porsible that the anluale would be lcrc recLrtant to thc cffectr of 62 la{ r o! H +l EI rP1 u1 lJ! ul n (Yl m fa H ox Az EE 4 C' ao{tI {o I t{.r aa D ,NN oro n turE F{ ,-l F{ F{ gtr +l +l +l +l BB H o AE o o o$ E.. aa q 8B EO9 Fl u1 ':cl lO ':ttl AH t1oF F('t t! I'r ('r A E! Io ' Hfi gt lOtlr0 ElEH aaaa DII tNrfloo gDH Ur,{r{l.lN 6E +r +t +t +l AH{ *f,'+tg @ o o t! NOIOA tE ...... o I Qts >rOgF{t! or ol F{ H OE (alf1FFol tr Nt rr H s8 tIEU otr @Nto@ (o t.r.t U6lF{ort! E' s{F{r{A Afi dtn HH qEi +l +l +l +l .P Ht4 [E N O O O dE . r . . .: 0. 8E rlF{roN10 olorlfEl1 A'nFOol tI N T h H[Hr( oE{l. U}l N ro ro rrt r{ ({ lO' aa a o frH o(., 0 (o@ co HU irt{ N NF{ N l{O ? BH E* +l +l +l +l I . eE oo o oo \o o co EO Fl U-l t aa o-. . . 6ri ft TI(} Atf F d Fl O O+, ll. lRrr to OrO F d y1 rn $.5 H 6t" H O At*t-{ E{ tntno F{CAFIo d or, d h gt{t on ci hr H o E o \trrotrr cr {ri Ir +J E ''.1 Ur l{ O Qbl O 0 $a urauS llJ4 oJ4 0.l. oo0 cr)ino "e\ rr\ C\ d+,*, OtoF{F{Gl aEr o Ur dq, tn r{ ur do =, tLa o >o,o +, t, (H O-l l{F{ 4E IJ H H E '{F{AEOT roulr'llnrrll r4 H z rr O'---€M. P. Gontrol p. butbocopninized G--$U. 90 CT O---{ C. F. Control ({ C. F. butbocopninized - trlo loo 80 2 E o o- E 70 a lrj alrl G z 60 UJ o C) ao- E, lrl '50 o E lt UJ trJ G, 40 J f l- U' o a ,30 (rtrJ G o- F .zo z z o lrj ,to ie = 5lo15?o LoG DOSE - 24 2 Sallne daily for 1OOO r Control One animai t-!.Led within 5 daye for Group I houre after radl-ationl all anir,als were dead in thrce tf,eekg. 3 40 rrgy'rg bulbocatrr- 8OO r One anlmal died Ytthln 72 nino dally for 5 houre after radLatlonr onIY days one anLmal sun/ived after 3 weekg. 4 Sallne daily for 8O0 r Control One aninal died 48 hours 5 daye for Group 3 after radlatlonr 4 aninals died vLthLn 3 rreelcs. 5 4A wg/kg bulbocap- Control No death or other iLl effects nine daily for 5 days for croup I wcre obgenred within 3 weeks of treatment. 6 40 Wtkg bulbocap- Control Ho death or otler 111 effects nine dally for 5 daYr for Group 3 hrere obsen ed Yithin 3 Yeeke of treatrnent. ts rABLE X RADIA:rIOtr PTIrECTXON AETtsR CErcUIC ADS{IITISERATIOS OP BI'LBOCAPUIrrE 56 DrgcuESxou AUD @rcLUSrorS |ltre changea ln thc circulatlon followLng the j,ntravcn- ous lnJectloa of, 5-ET have becn the cubject of much diaeur* BIon. In doge, a trl.phaolc recponEe of, thc blood prcaourc has been rcported, conliltlng of a fall folloued by a amaIl prearor actLon and then a prolonged fal1 of pres- gutr6 (S4, 9.277\. I[he raaultr of this inveetigatLon, horrever, ghwcd a pure proaror actlon at all dosee except the snallert when a depreafor roaponre t aa occaaionally aoen. 'lhcre var no lnltLal translent fall and no aecondary prolonged depreeror effect. llhe increase Ln thc prelsor relpon3e waa accoopanled Ln aLl experimentc rLth an Lncreacc ln the contractl,le force of thc myocardLum. 1!he preesor effcct producod ry ecrotonLn mlght be eauaed b1z a rlmlnthoadrenal stl,mulating nechanisn. 'll}dr agent .e€rna to act atrongly on the adrenal medulla rlncc Lte preuor actlon rras reduced by about 60 pcricent ln adronalcctqnized anirnalc. Allo, a dLreet actj.on of, cero- tonin on the rtorcr of cateeholaml.ncc at the poctgang- Il.onlc norive tcrtslnals sGorlt to be rerponrlblc for the prcsaor effect oboenred in an ani:roa1 aftcr adrenaloctmy. lfhe ncchanisn through whlch acrotonln relcaees catec]tol- amines fro tlre adrenal mcdul}a ic not knotm. It ie 67 probable, he*rever, that this releaEe occura by ctinula- tion of the ner:\re innerrrating the grand by choltnergLc ncch- anisms (11). Reserplne ls knoryn to deplete the eerotonln and cate- clrolanlne gtores of adrerrergLc netlt/e endlnge and to act ln the EtmG way in the braln ln addltlon to the adrenal medulla (32, p.I73). [he levcla of s-IfT and norepinephrine in the braln of Bome apeciee deeline in paralle1 after reserpine (Zf) - The relatLve importance of the central and peripheral effectr of reserPine ie regulated bnz the relatLve sensi- tLvLtiec of tlre central and peripheral gtores of norepi- nephrine to the releasLng action of this drug. llhe catecholamine gtoreg of the adrenergic nenre ternrlnals and the adrenal medulla ce knc*rn to be highly sensltive to tho depletlng action of reeerpine (32, P.174). lhie depletlon ig probably reeponcibl.e for a marked reduction of the 5-m prccaor reaponaes, indicatlng tbat s-Uf depende on t}e raloase of catechoLaminee for alL or moct of ite preosor acti.ons. Ae discuesed earJ.ier, the depleting actlon of reacr- plne rnay have a eentral as well as a peripheral cmpon6nt. 68 Emrever, lt is not knorctr whether the depletlng activitLeg of reserplne in relation to 5-IIT have a central con5rcnent. The actl,on of reeerpine on s-ItT io rsrenhat comparable to that of tyraniae. fhis agent hae been found to have no pressor action j.n reserpinized animals (87, p.362). Sincc this agent is kncnrn to produee a pressor responae by re- lease of transp-itter aubstancee from thc adrenerglc nernrc end:lnge, the abcence of prectsor response in the reserpinlzed ani$als may be interpreted, ag conplete depJ.etion of there substancea 187, p.362) . Ihe preasor action of S-If[ In t.he reaerplnized animale, in contraEt to tyranrine, was not cmrpJ.etely abollshed. .|[hlg may be due to uneven depJ.eting action of reserpine in diff,erent cateeholanine stores (32, p.I74) . In fact, it ia poaei.ble that i.nadequate re- serpinizatj.on occurred and that there wae only partia). de- pletion of some of the organs. In ordcr to qonfLrm the poeeibility of tho releaEe of transrritter eubgtances frm the nerrre terminale in tlre preasor rerponaee produced by 5-[If, a number of agents knowa to either deplete or ir&lbtt ttra releaee of gub- rtances rere used. Among theEe h,ao guanethi*lne whLch cauaea an early release of tranornitter eubetanee and then lrrhlbltc thlc (32, p.2o4). trt probably hae llttle effeet 69 on tho adrenal Ltrelf. U;ron adminiEtration to En adrenaLec- toml,zed anlaal there should be no pretaor rosponao to lator adnLnlstratlon of a drug that acte try euclr roleale. 5-m undcr tlreae condltiona ahqrcd no preaaor r€8ponsc, givlng further cvLdence that thc preceor response of tlir agent Eay bc due to the action of, oyetolc cateclrolamlnec aE a result of etlnulatlon of the adrenal medulla and the ro- Lease of ttre catectrolaminee frw the clmtrnthetic ctoroa of the lrcstgangllonlc ncrrrc tcml,nall. If,re co,ntractile force rGsllonae of S-EI f,ollering adrcnalectwy and guanethldlnc war reduced but not com- pJ.eteLy aboLlehed. ttrle uay lndLcate that s-tIl ic aetlng on amo receptom of, the hcart conpletely lndependent of tlre eatecholanine rcceptora. ltaterlal further explaining ttrls lg dLccumed belon. Anothor agent that rerenbles a Eiuanetlidlne type of action 1r eocaJ.ne, whlch la reported to prerrent the re- leaEs and uptake of, catecholastines frm diffcrent storec (45). Cocainc lc knoryn to aboLlsh thc prersor action of tyranlne, probably bV inhlbiting tho releage of trans- mitter nrbrtanees needcd for tyramLne prcaaor responie (89, p.346). llhe cmplete lnhlbltton of 5-tm ptesoor rc- apotrre ln adrenalectomlaed anlnale follohrlng cubcequent 7A doEcg of eocaLne could be cxplalned on almLlar groundl. lfhia could be regarded as addltlonal errl-denee laadlng to the conelueion that ralease of ryurpathetlc egbctanccr fror tha adrenal medulla and adranergLc ncrr G cndlnga eonstLtutes the PrlmG meehaniscn for 5-lfT Prellor rClPoIlsC!. I,he 1rcaelbtllty of the involvenrent of hlctanlno Ln thc preator actlvtty of 5-m haa bcen tuggelted (9). 5-m has been shown to release hlstanLne from varlotre lrolatod anl,mal tLagues (25) . In thlr connection, thc rcsultr of lnteraetion between hexamcthonLrmr, nlcotLne, and pyrlbcn- zarnl-ne wlth hletanlne clted frqn the literature can be aeen Ln $rc introductory Part of this paper. Hexastcthon- |um, a known competltlve ganglLoni.c blocker, falled to re- duce the preceor effects of 5-Hf ln thig invcati.gatLoni lnatead, a marked potentlatLon of thesc effectc waa obacnred. A slrnllar trrctcntiatlng reaponte after hcxa- methonlum has been reportcd for hiatanl'ne, epLnephrl.nc, and norcplnephrlne ty ot-her invoetigators (8U . A trrceaLble explanati.on for the potentlatlng effcct of S-IfT obeelved Ln this investigatlon and hlgtanlne reported tryr othera may be that perlpfieral end organE develop lenlltivtty to eplnephrlne and norepLnephrine. EgnelLn har added aupport 71 to thlr trrcstulatton tryr rhorJ.ng that the nictltating mern- brane and the rulrnaxlllary glanda becqne progrcsrJ.vcly moro senrltlve to epinephrlnc rrtren ganglionic block ls malntalncd for two to threc weekg tryr lnJecting chloriacnd- rrpi.ne (a gangllonlc blocklng agent) twLce dalty l2L, p.26). !!!re potentlation of 5-HT and hlstamLne responses after hexanethonLrrm could therefore be due to the epJ.naphrine, rcleascd by these agentr, on tlre sensitive peripheral orgiana. A hLstamine releaaJ.ng mechanigm ie suggested as actlng in lntaet dogs and catg only rrrhen 5-IIT J,s given by contin- uoua lntravcnouE Lnfusion (55). Bunag and Walaezek, hotr- ever, have reported that Ln chlckene higtamLne Ig released even when 5-m Ls glven }rt' single lntravenous inJectione (9). lfhorefore, it was cuggected that the pressor effect produced by aerotonln might be due to the knorvn slmrpatho- adrenal ctlnulating actlon of hLctamine (9). It ls also porgLblc to attribute the etlnulatlonE of, ganglla by agentc auch ao 5-ET and hlgtanine to theLr inter- actlon wlth eltcs Ln the ganglla not aenri.tlve to acetyl- chollne and therefore reslstant to blockade by tradltionel gangllonle blockers, such a; hexamethonLum. Xt ahould, hoyever, bc noted that 5-8T and histanrLne could have en- tircly dlfferent receptor alter Ln the ganglia. 72 |[he bl5*raaic ganglloni.c blocklng actlon of nlcotl.ne dld not produce any appreclable changee Ln ttro prGrtor aEt1on of S-ll[. In contrart, other lnveatigatorg have rcported lnhibltlon of hlrtrrnlno prelror actlon after tlre fl.rrt pharc of nicotlne actLon (blod 5-Httl contraetlle foreG. llhlr agent Lr kncnrn to eauso co6- plete bloclcado of, nyocardlal rcrponrea to epinephrine and 74 norepl.nophrine by a cmpctittvc type of entagonlm for the Byocardial recelrfor; 128, p.10). It Lt polriblc that 5-m and cplncphrine or norepinGlihrtne havG a mutual myocardlal rcceptor. Ectrrever, the etrldGnc6 prercntod earlisr 1B thl'a paper lrciate out that thcre arc Probably cone 5-ET sPcclfLc rryroeardLal receptor! lnd€pcndant of t}1c cateeholaml,nes. ifhlg doer not rulG out ths lrcerlbiltty tlrat DCI could also block thcre rsccPtora by e conPetitlve mechanljp. llhe ef- fGct of DCI on t}rG blood ProEturo rcapon8e of S-lfT could be attributcd to lnrtlal lnhlbltlon of the rclease of gangllonlc tranmltter lubltanccc. Ir ths Prcltor actl,on of 5-ET centrally uodiated? Probably tlot. Chomlcal sympathcct@y by procaine in addl- tion to vagotoy failcd to caulc any EqaaurablG changes on 5-E[ trG8lronge8. llherefore, lt nay be concluded that tlre pr{rnrry uec*ranlm f,or 5*ffi l}rGt.or rGtlronte l.g ttre gtLmu- latlon of, adrcnrl nedulla and thc pootganglLonl.c adrcner- gLc nenrc cndingr lcadlng to thc reloaee of catoeholalnLne and a cgnsCqucnt precoor Action on t}e blood BtrQasurc. lfha contraetilG forcc tstLon of 5-ET lr probably a product of tlrc intcractlon of, the rclearcd anlneo wltlt t}te myo- eardLal receptora aa w€II al thc actj.on of 5-Ef on somc 75 S-Iil-opecif,ic receptore. Ihc sccond phase of thLa regearch waa coneerncd wltlt ttre intrlnaie propertiaa of bulbocapnlne and lta inter- action wittr S-HT. BulbocapnLne has been chqlf,n to produce a c&tatonic qmdrme ln frogr, guinea Pigr, rabbLta, dogr, and catr (39), In theee opeciea the adminictration of bulbocapnlne le accompanfed by exceslivo lacrlmatlon, ralivation, elcnred reapiraticr, and reducod eardlac tone (39), Doset ot 10 m9ft9, 25 rlg/t.g, and 50 rrg/(g of thic drug in anorthetlzcd dogr cignLficantly roducad the artcr- lal ryrtollc, diaetolic, and neanr prcssurea. llhc rolponrc to contractlla force wrs not congistcnt. ![hte inconrirt- €ncy could bc due to variabillty of renponres to the cm- pcnlatory rlzalnthctlc gtinulatLon rerultlng frcur a f,all in blood prGttura cauccd bry bulbocapnine. Electroeardiogrramr of ccrperlnontal dogr ghqed aome ehanger whlctt were aG€n ln mort but not al,l of thc anLnalr. Uelng lcad XI, thc p uave tcndod to bc prolonged ln noet caa€. and the QR8 intcnrnl, appeared to be abortensd and lengthened, Lndicatlng a modsrats prolongation of ventricular contraction tLne. Eha effeetr of bulbocapnine on tJle blood preasura, contractile forco, and the E(l could bc due to tho changer 76 exe*ed by this agent on the quantlties and the normal functions of potaesLum and histarnine. Bulbocaplrine Lc knqrrn to irrhlbit dianlne oxl"dase (histaminaae), which is an enzyne reaponsible for the destructlon of hietanlne (13; 14). XtiE may lead to accunulatLon of hiEtamine, an agent wlth j.nhlbltory actlvltiea on the blood pressure and contractlle force. Resultg of thia Lnvestigatlon have shqrn that the serun potaaaLrrm level progresclvely decreaseg Ln tha firet hour follqring bulbocapnJ.ne a&ninistration. & Bulbocatrmfuie produced a conplete blockade of the pree- cor actlon of s-If,I on tho blood proasure and contractlle force of the dog, but produced only a. partial non-selectivo blockade of, the catecholanine presaor retponces observed ln thle study. Xhere rtras no e"nidence of an eplnephrine revergal a8 reported by Ctralman and lfalaszek (92). lfhe mechanlsn of the blockadc is difficult to explaln. Ery- ever, the changes exerted on the norunl atatug of trrctaaeium and hirtaurlne, €.9., infhur of, potatglum and destructlon of hJ.rtaninace, could have important bearing on the mechanLm of the blockade as mentLoncd above. Eistamine has been shcnrn to increase the peraeabiltty of capillary membranec (76 1 37) . Coppola and Dltrnlna have reported a hlstanLne rcloase after long term lnf,uel.on of noreplnel*rrLne (15). llhc rcleare of hlst*nLnc dccreaEol 78 the responslvenegs to noreplnephrine r*rlch could nean an Lncreage ln the cellular permeabillty to eplnephrine and norepinephrlne rtorage sites leading to lncreasod uptake of theee aminee. !$rerefore, lt ls lrcseib1e that bulboeap- nLne, Iryr allouing an accumulatl.on of hlctamlne ln the ryetem, could caurG an Lncreased cellular permoablltty of etoragc rl.tca to 5-E ag well ar eatccholamLncr and pro- vl"des lnhlbltory actlon b1z LncrearLng tJrc uptike of thcae agcnta by ttrc tlrgue etorql (probably morG selectj.ve u;>. talcc for 5-ET than catecholarnlnes). ![hG data reported ln TABIfi VIII are ln f,avor of thig tr)ortulatton, rLnce antlhj.rtaminc (PBA) lnJectlonc prLor to the adnLnLatration of bulbocapnlne to rme cxtsrt countcractcd the tnhtbltory act{on of t}rLr agcnt. llrhla could m6an that t}re lncreaged ccllular pcmoabtlLty caurod tryr hletemine Lg blockad, at leact partlally, leading to a fall in tLrsue uptalce of 5-m and eatccholamlner and elqvatlon of rerponlca to therc agcnta. Thc cffeet of bulbocaSlolnc on the potasrlrn lcvol of rsrun or tlccue (hcart) war dLscureed carller. llhcre changel could alco provldc an explanatlon for the blockJ,ng action of bulbocapnine. Potarafu:m hac a dLrest dllating cffcct on the arteriolc and 1r knourn to dccreacG thc 79 of,faetlverrom of varoactlvc rubrtancct by altering tle ccngltLvLty of thc snooth uutclc. PotrssLre lon la also Lntlnately lnvolved Ln thc neurmuccular tranefcr of Ln- pulrcr ln the nerye ccllr ac wcll rr slmrptlc Junctlonl. 'lfhe changer Ln the mcmbranG potentlal, erucntlal for prolrgatlon of Lmpulcea, arc entlrcly attrlbutable to LonLc movcraenta, nainly lrctaorLun and rodium, acrorg the surface membrane. llhe rertlng trntentl.al for K lon lc re- portcd at about 90 mV. At t*rlc polnt an equLlibriru ie rcached betrecn the eflux and lnflurc of K lon. At higher lsvale.of mmbrane potcntiale, o.9., ll0 mY, there Le a net lncrorse of K Lnflux o\rar the efhus, a condltLon knqrm aa an after-dclnlarlzatlon. It was ttrorefore eoncluded that lf bulbocatrmJ.no through rme mechanlm altered cell perneabtllty to Lncrease the Lnflux of K lon srrer a rela- tively long perlod of tine a, blockade of ncutromuacular lm- pulaee tryr ncano of a total and prolongcd dcpolarizatLon would be reached. ![he posalbtltty of a hletamlne-lrctaaeltm Lntcractlon rhould not bo cvrrerlooked. A rire ln hlgtamLnc concentrt- tlon by bulbocapnino may lead to an increare of the cellu- Iar perncabil,lty to Lonc euch as potassl,um whlch can orcplaln thc rapid loce of thle isr frm blood plaama. 80 Bulbocapnlne parttally blocked thc prersor actlvLty produced by 10 ng/*g doces of potasglun chlorJ.de. Kcl, at thc doree givcn, would bc cxpected to atLmulate the adrenal glanda and the lncrease l.n contractile force Lt produccr 1g mort lLkely due to the releaeed aplnephrLne. rn tlrlE cage, ar with s-ET and catecholanLnee, the bloeklng aetlon of bulbocapnLne eould be due to eLther morc rapid uptakc of cpLnephrlne by thc tlrrue ctorage rLteE or a dceeneltlzatLon of vascular bedr to the aetlon of preecor agcntr inltlated lry potassLuur. Dulbocapnl.ne war ahotm to have good blocklng actlvlty Ln rererpLnLzed anlmalc, tndl- catlng that catectrolamine or S-ffi release is not Lnvolved in bulbocapnLne actLon. l(he possibtltty of central nenroug eyatem lnvolvemcnt ln the blocklng actlvlty of tlria agent was also elLmi.nated since chemlcal rlznpathectoay and vagotomy dld not produce meagurable changes in lte blocklng actlvlty. In addltlon, thoco agente that caused a reductlon Ln the amplltudc of the presgor effect proved to potentJ,ate the blocking actJ.vlty of bulboeapnine. Among thecc wGre reaerplne, DCI, and chefirleal alzulntlectcmry. An lntereatLng obseryatJ.on was made of the cffects produced Ln animalg treated for five daye with noderate 81 doseg, 25 mg/kg, of bulbocapnine. lfhe blood prersure and contractLle force rGtponges to doscs of 5-B'? in thece anlmale t €re markcdly augmented. lf,he effect of the catecholaminer on the blood prcssure wal not changedt hwever, the contractll,e forec rGaPonte \r theae agente waa narkedly potentLatGd. She regultg rec€mble the poten- tiatLon of catecholanlne rGelrontec in reaerpine depleted dogrs. Eere, hmener, tlre depletion secms to be of 5-Ef. ltro porsibiltttes Eay exllt. Fimt, bulbocapnLne may be doplctlng the perl,pheral atorot of S-ET, cauring the perlptrcral rcccptorr to becqne hyperaenrLtLve to eubsequent doecr of 5-ET, and, aecondly, bulbocapnlne may havc in- crcaced the uptake of 5-m }r!r tllauc atorage rltes leading to an almort total etoragc of S-ffi Ln a bound form, and al in tlre fi.rrt cass, tlre pcrLpheral receptor became hlper- cenrltlve to rubeequent doaes of "freG" 5-E.[. lftre a&ainia- tratlon of an acute doae of bulboeatrrnlne, 25 ot 50 mgll<9, in ttre chronically bulbocapnlnlzed anLralg, produecd con;- plete blockade of eubscquent 5-ffi doreo. lftrc mechanirn of bLockade Lr probably the eane aa for butbocapuLne aEtj.on in non-treated animalc. InJectlone of 5-llT and andogenous rcleage of thlr amLne by agantg auch ar rGlerpl,ne have been reported to 82 increaee the radioprotection in ylvo (86, p.73). Bulbocap- nine sae ueed to examlna whcther or not thLa agent rorearcg s-IfT and if Eo to tegt lta radioprotectLvo eapability. llhe rerulte shorred no apparent protection agalnrt radLa- tj.on in bulbocapnJ.nc troated anlnals ovor the control anlualg. lthlg uay indieate that bulbocapnlnc docg not releare free 5-Ef ln the cycten. 83 STDTI,IARY 1[he purpoee of this atudy was to examine the i.ntrlnsic activlties of S-hydroxytryptamlne (s-IfT) and buLbocapnine and their Lnteractlon Ln regard to blood preseure and contractLle force in the dog. 1[he reeults of the lnveg- tlgation ehorsed thatr (X) Intravenous inJectLon of S-FT to anesthetJ.zed anLmalg producod a pure preaaor responrG at aLI doaes uscd wlt} a rar6 depreseor reaponse on the blood preEsure component Eeen only with the snalleEt do8G. (2) Adrenalectomty diminlshed the 5-IIT preaaor retponseat hourever, tt dld not completely abolich theee effectg. Re- serpLnJ.zation alco tnhlbited t-he s-ItT reaponsea. Coeainc and guanethldine abollghed the presaor effect of S-HT on the blood preaEure of the adrenaLectomized doge. It was therefore concluded t}at stLmulation of the adrenal medulla leading to the diseharge of catecholarnLneg and the releago of the tranrmitter gubataneca fron the postgangll.onic adrenerglc nerrre termlnalr are probably rcsponslble for 5-Hf preraor effect on the blood preaaure. Pergiatence of a pressor responae ln ttre contractlle force of the guanethldine admlnlctered adranalectmrlzed anfunale and a potontiatlon of thlg reaponte Ln hexanethonir:m pretreated 84 anlmale eould be explained by the preaence of solective 5-IIT receptore ln the myocard,lum completely differont frqn the catecholasrlne receptors. (3) A hlttamlnr lnltlatcd rympathoadrenal gtimulatlon as a poaeible mech- anisn of tha 5-IlT pressor actl"ons wae dLsregarded. fhie waE because of a lack of pressor responee tryr intravenout lnjectionc of histsamine J.n addl.tion to the dlfferoncea obserived q&en s-HlI was glvon after nlcotlne and pyrLbenz- amine and thoge reported by others for hLetanine. Bexa- methonlum produced a potcntlat.Lon of the 5-BT relponaea slnllar to those reported for hJ.atanlne. It wae coneluded that tlre depreaEor comlronont of htrtamlne tendr to be ob- gcured fry t}re presaor actlvltLee of 5-Im. (4) Dichloro- lsoproterenol (DCX) reduced the prccsor reaponse of s-Hf on the bLood prGssure, probably through an ir&ibitl.on of the relcaae of trancmLtter cubatanees frm the adrenergic storea. llha contractile force componant of 5-HT war abollched after DCI, probably due to a coapetLtlve antagon- lgm. Chemj.ea1 elmpathectmy and vagotqny failed to ehci, any changce ln the reeponses to 5-IIT, whLch was lnterprcted ao & laek of eentral involvement in 5-HB preaaor reapon.at. (5) Bulboeaprlne cauged a rcduction in the blood preasure, 85 and the contractilc force and BomG EKG changer. llhc rGne potaceium level wac nrrkedly dccreaged wltlr 3ome incrcare in the potaceium levcL of myocardial tlrlue. llhe clranger in the potasoiun lcvel arc believed to bo rufficlent to explaLn the intdnslc actlonr of bulbocapninc. (6) Bulbo- capnine inhlbited the 5-IIT precaor responaea orr the bLood preasure and the contraetile force. Ihe irftibition of, catechola'n{ne rGspons€o hraa only partial, and at no tlme was tlrere an epinephrine or ethylnorepinephrine reverlal. fheref,ore, the poreibility of, an al.pha or beta adrenerglc blocking actlon aa a mechanism for bulbocapnine tnhibltory effeet wae diacredited. ![he bulbocapnine inhibltory actLon waa Gxplaincd on the baeie of K+ atrifte tryr ttrie agent. (7) Doga, treated chronLcally wlth bulbocapn:lne, ehowed rtrong potentiation of 5-IIT pr€asor eff,ccte, probably due to an increare in thc 5-Iilf uptake by the tlrsue atorca. (8) Chronic tulbocaSnLnc treatnent of rate for one week failed to shou any changcr in the eunrival, tin€ when the aninalc w6re lrbjected to X-lrradietLon. 86 BXBLIOGR.APET l. AhlquJ.et, R. P. A rtudy of the adrenotropic re- ccptort. American Journal of Phyrtology 153r 586- 600. 1948. 2. Anln, A. 8., T.B.C. Crarford and iI. H. Gaddrm. Ihe dlctrlbutj.on of rubrtance P and S-hydroqrErlpta- plne ln the central neriyout syst€m of the dog. ilournal of Phyriologpr L26r 596-618. 1954. 3. Barlan, R. B. and I. Ktrarl, Actlon of rqnc analogt of tryptaninc on the irolated rat utcrur and on tha leolated rat fundus Etrlp preparatlong. Britigh ilournrl of Phamacology l4l 99-107. 1959. 4. gcndltt, 8. P., R. &. Wong, I|1. AraSe and E. RoepGr. S-HydorxytryptamLne ln maet celle. 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