765 sBRCM
ACTIONS OF TYRAMINE AND COCAINE ON CATECHOLAMINE LEVELS IN SUBCELLULAR FRACTIONS OF THE ISOLATED CAT HEART
H. A. CAMPOS, R. E. STITZEL AND F. E. SHIDEMAN Departm.ent of Pharm.acology, University of Wisconsin Medical School, Madison, Wisconsin
Reprinted from THE JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICB Vol. 141, No. 3 September, 1963 Copyright. © 1963 by The Williams & Wilkins Co. Printed in U.S.A. H.eprintPd fn.1n 1 T11r_: .Jcn~H :\A L 01' 1-'1-t.\H\L.\f" OL O G Y .\ K D E X PERl~lF ::-.'TA L TrrEHAP~Tl'H·:-; Ynl. 1-11. :\o . ;) :-\1 ~ ptr111hPr. (!lü:l Copyrigh t- ='D 1 96 :_~ IJ y T I.e- Williaws &- Wilkins Co. 1~ r i 1 1 ted i 1i { ·.8.A. .
ACTIOl\S OF TYRA;\II~E AND COCAI::\E Ol\ CATECHOLA~Ill\E LEVELS Ii\' SUBCELLCLAR FRACTIONS OF Tl-IE ISOLATED CAT HEARTt
H . A. CA.\'lPOS/ lL E. SlTl'ZEU AND F. E. ::-: IIIDE.\IA:'\é Depart111en/ of Phannacology , l ' nil'nsit¡¡ of Wisconsin !1ledirn l School, .llar/i.,on , W i3consú1
:\ ceeptcd fo r publical ion .\foy 20 , l!Jl;:)
Burn ( 1930) ob>'crn:d that elerntion of diffcrential ('<' ntrifuµ:ation anc! ~hmrnd that in t.hc circulatinµ: lewb of cpinephrinc in the eat by reserpinized animal, thc uptake of infused a.dministration of thc amine cnha nced thc vasu norepinephrine \Yas greate:3t in the " soluble" all(I constridor ad.ivity of tyrnmine. Subscqucntly least in the "particulatc" frar tion. This find inµ; many :)tudies havc suµ:gc;:;ted that the 6ympathu suggestcd that restoration of r e spon~iven cs s to mimetic effect:; of tyrnmine are dependcnt, at tyraminc by adminis tration of norcpinephrine to lcast in part, on thc prcsenrc of eatccholamincs the rcserpine-trcated animal is a rcsult of in tissuc6 or bloud. One of the more significant re1::cnishrneí1f of _th¿.·'j'soluble'' fr_action. contributions of this naturc is t h.e hnciing by Bum J he hypothes1s tpat t~-rarmnc t>xcrts it:=< a nd R.and (1958) that admin~ :;tration of nor stim11latory cffect prfma rily through rdea;;c of cpinephrine to the catecholarnin,e-dcpk ted animal catcchula mines from storcs of norepincphrine in can rc:;tore the ,-tinrnlatory action of t.yramiuc. thc ":.;oluble" fraction of thc ccll has bern test.ed Such a re.-; toration of re~pon ;; i vf1i~t0 t~ramíne. in the present work ..· Sinee coeaine antagonizc ..; has abo bcen obsen·ed m the ITT' 1ílcted, 1sola·ted, ..the sti.mulatorv Úfferts of tvraminc (Taintcr and heart of thc doµ; ( Ucjrabla~ · a el al. , l ()fiS) a mi the Chanµ;, 1927;. th1·;;;·' ami .Tainter, 1931) , pre- rat (Axelrod et al., 1962). sumably by prevcntinµ: it. from relcasinµ: <'ate :\Iuschulh di scovcr~· (1900) t.hat re~erµi n c c hobmin e~ from their 4orage ,;ites (Flcekenstcin impairs the uptake of liorcpiucphrine by the rat and Storkle, l955; :.Iacmillan, 1959), its capaeity heart ~ u µ;gc,;te d that thc rcstoration of the t o antagonir.e tyr::iminc-indueed alteratiuns in stimulatory action of tyramine i. .; not relatcd to suhedlubr !"Oll<'t'ntrntion• of <'at eC' h o lami11 p~ \l·n:< repleni,;hmcnt of norepinephrine in ti~.-;uc :4ort>:<. examincd. H owever, further work ha" shom.i tha t re.,crpine does not eomplctely :ibolish the uptakc of l\IETH UDS. i\lalc a nd fernale <'at s weighing 1.8 tt• norepincphrinc by thc !'at kidrw.\· ur utcrus '1 .0 kg werc ancsthctizcd with et.her and ki ll ed b~· (Penncfathn all(I Ha nd, 196()) or b~· tlw doµ; cardicctomy 5 minutes after intravenuus adrninis· of (Campos and Shidcrnan, l ()()2) aud r::it heart tration hepa rin (500 17/ kg) . Aftcr remo val f rom thc anilllal, the heart was pl:1ced in warm Krebs · (Kopin et al., 19G2). Henscleit solution. This sulutiun was used as Catecholamines havc bcen d t>m cm~tr: t tccl in thc perfusion fl uid in a ll cxpcrirnents and cun particle~ "·ithin the erll w ~eH·ral t.i:-:-;ues t :üned in 1 liter G.n g :'\aCI, o.:l5 g h:CI, 0.28 g (Blaschko a nd \\-ek·h, l 95:3; YOll I:uh·r and CaCL, 2.0 g glucose, 0.1G2 g XalLPO, and 2.1 g; Hillarp. 1936 ; W cil-l\Iallwrbe and Bone, 19;') 7; NaHCn ,. Aftcr li gating t he hranchcs of t hc aorta O ~ tlunc! et al., HJGO), ineluclinµ: the rat hcart :md re n10v ing the pcrirardiurn, the heart was per (Pottcr and :\xclrod, l 9G2) ami tlw doµ; hcart fnsed through thc aort:i by means of an Auderson (W e¡.>; ma n a nd Kako. l\Jül ; Campo.-' ami Shide Langcnd11r ff a pparatus. Thc ¡)('rfnsion ílttid w:\;.; at n a man, l 9fl2). The la> T ABLE 1 Ejfect of tyrainine on concentrations of catecholamines in subcellular f raclions of the isolated cal heart -~r: ~-~~ ,1 Ca t~·c·~o laminc Concentration"- µg/ g of Fresh . ~i ssue ·-_ ! Recomy (%) 1 Co~~:~~ of Expts. . er use wi . 1 Coarse Particu late Soluble Whole i Tissue (%) 1 fra ction fraction fr action homogenate 1 ------·--- A tria ---~·------·-·------30-rninute pe1jusion 1 5 ! K-H ~ 1 0.2G ± 0 .051 0.29 ± 0 .03J 0.GO ± 0 .051 1.47 ± 0.071 79 ± 7.82 84 ± 1.19 6 1 T y- 1 0.11 ± 0.02 O. lG ± 0 .03 0.29 ± 0 .03 0.71 ± 0.07 80 ± 6.35 1 80 ± 5.64 ! ramine< 1 1 1 60-minute pe1jusion 7 K -H 10 .22 1 0.29 ± 0 .071 0.30 ± 0 .04 J 0.43 ± 0 .06¡ 1.23 ± O.lG, 83 ± 4.24 ,83 ± G T y- 0.07 ± 0.03 0.19 ± 0 .04 O. 27 ± 0 .04 O. 77 ± 0 .09 69 ± 4.26 82 ± 3.31 ramine 1 1 90-minute perfusion 5 K-H 0.20 ± 0.041 0.32 ± 0.05, 0 .38 ± 0.071 1.09 ± 0 .13'¡· 82 ± 4.75 180 ± 1.14 4 Ty O.OG ± 0 .02 0.10 ± 0.02¡ 0.21 ± 0.03 0.41 ± o. 06 88 ± 4 . 50 77 ± 2 . i3 ramine Left Ventricle 30 -min·ute perfusion 5 0.43 ± 0.041 o.65 ± 0 .011 0.42 ± o. o4 l 1.57 ± 0.13', 96 ± 4.43 ¡81 ± o.88 6 ! ~~;,~ 0.23 ± o.o3J o.34 ± 0 .01; 0.21 ± o .o3¡ 0. 82 ± 0.10 92 ± 5.86 ¡82 ± 0.11 ramme 1 60-rnini¿te perfusion 7 K-H 1· 0. 35 ± 0.061 0.59 ± 0.071 0.35 ± 0.04 1.42 ± 0.19Í 92 ± 3 . 93182 ± 1.13 () Ty- 0.21 ± o.os¡ o.37 ± o.o9¡ o.2G ± 0.02[ i. 01 ± o. 17¡ 83 ± l. 90 85 ± l. 90 nunme 1 90-minute peijusion 5 o.32 ± o .o4 ' o.51 ± 0. 11 1 o.3G ± o .oo¡ i.32 ± 0.181 94 ± 7 . 62 182 ± o . 38 4 1 ~~~ 0.20 ± 0.04 0.22 ± 0.04 0 .25 ± 0.05 0.G4 ± 0.09103 ± 4.88 83 ± 0 .G5 ramrne 1 1 1 i i ~---~ ----- ª Calculated as norepinephrine a nd expressed as a mean ± S.E. 1• Krebs-Henseleit solution. e LO µg / ml of perfusion fluid in ali experiments. decrcase in thc leve! of catccholamines in the the presence of thc highest concentration (40 "particulate" fraction occurred only in t he µg/ml) of cocaine employed deplction again ventricle (P < .05). At a concentration of 20 occurred when the concentration of tyramine was µg/ ml , cocainc exhibited no significant depletinp: increased to 10 or 100 µg/ ml. However, t he effect on either fraction. A conccntration of 40 extent of depletion was never as grcat as that µg/ ml of cocaine maintained catceholaminc induced by 1 µg/ml of tyramine in the absence lcveb in both "particulatc" anti "soluble" of cocaine. In the atria a good correlation fractions highcr than those of the perfused control (r = 0.997) existed bctween catecholamine levels and equal to, or perhaps greater than, those found in the "soluble" fraction and concentration of in the nonperfused heart. cocaine. A similar relationship did not exist in The eatccholamine dcpleting effect of thc case of the "particulate" fraction (r = 0.220). µg/ ml of tyraminc was progressivcly decreascd in A significant positivc correlation (r = 0.849) the presente of increasing concentrations of bctween conccntration of tyramine, in the eocaine in the perfusatc (fig . 3 and table 3). In prcscnce of cocaine, and degrcc of depletion of 1963 TYRAMINE A.'\D CARDIAC CATECHOLAMINES TABLE 2 E.ff ects of tyramine and cocaine on concentrations of catecholamines in siibcellular fractions of the isolated cat heart --P-er-fu-s-cd_\_vi-th-l~Catec~o~:_m~n_ e Concentratlionª~µg/g oí IFres~ ;i:~~IJ -Re(%J°ry .. Water .'.\o. of Expts. Content of ' Coarse Particulatc Soluble \Vhole Tissue (S·ii) fraction fraction fraction homogenate i ·------·-···------1 ----'------A tria 5 N.P.b 0.38 0.34 0.87 1.44 110 72 ± 0.04 ± 0.05 ± 0.21 ± 0.42 ± 13.46 ± 15.67 5 0.26 0.29 0.60 1.47 79 84 ± 0.05 ± 0.03 ± 0.05 ± 0.07 ± 7.82 ± 1.19 G Tyramine 0.11 o. rn 0.29 0.71 80 80 1 µg/ml ± 0.02 ± 0.03 ± 0.03 ± 0.07 ± 6.35 ± 1.64 Tyramine 0.07 0.05 0.21 0.53 t\2 78 10 µg/ml ± 0.03 ± 0.01 ± 0.01 ± 0.04 ± 1.18 ± 2.18 5 Tyrami11e 0.11 0.06 0.2G 0.53 80 77 100 µg/ml ± 0.02 ± 0.01 ± 0.04 ± 0.05 ± 7.85 ± 1.05 Cocaine 0.19 0.22 0.34 0.98 77 79 10 µg/ml ± 0.01 ± 0.04 ± 0.05 ± 0.12 ± 7.55 ± 0.77 Cocaine 0.22 0.23 0.52 1.06 91 80 20 µg/ml ± 0.02 ± 0.04 ± 0.08 ± 0.03 ± 2.38 ± 5.98 Cocaine 0.42 0.50 0.86 l. 73 104 73 40 µg/ml ± 0.07 ± 0.08 ± 0.19 ± 0.34 ± 0.t\5 ± 3.08 Left Ventricle 5 N.P. o.6u 0.76 0.t\6 1.61 128 78 ± 0.04 ± 0.08 ± 0.10 ± 0.08 ± 7.68 ± 0.58 5 K-H 0.43 0.t\5 0.42 1.57 96 81 ± 0.04 ± 0.07 ± 0.04 ± 0.13 ± 4.43 ± 0.88 Tyramine 0.23 0.34 0.21 0.82 92 82 1 µg/ml ± 0.03 ± 0.07 ± 0.03 ± 0.10 ± 5.86 ± 0.71 3 Tyramine 0.19 0.20 0.24 0.85 73 82 10 µg/ml ± 0.03 ± 0.01 ± 0.04 ± 0.06 ± 4.64 ± 0.41 5 Tyramine 0.2:3 0.18 0.28 0.69 97 83 100 µg/rnl ± 0.05 ± 0.04 ± 0.05 ± 0.09 ± 7.88 ± 0.65 Cocaine 0.25 0.39 0.27 0.94 97 78 10 µg/ml ± 0.03 ± 0.08 ± 0.04 ± 0.09 ± 5.41 ± 0.77 Cocaine 0.37 0.56 0.37 1.29 101 84 20 µg/rnl ± 0.07 ± 0.08 ± 0.10 ± 0.14 ± 8.54 ± 1.76 Cocaine 0.64 1.15 O. 79 2.51 114 82 40 µg/ml ± 0.22 ± o. rn ± 0.25 ± 0.80 ± 17.03 ± 0.96 ------·--- "Calculatcd as norepinephrine and expressed as a mean± S.E. " X .P. = :!\ ot perfused. Hearts were homogcnized immediately after removal from the animal. 'Krebs-Henseleit solution. catecholamines in the "soluble" fraction was prescnce of a fixed concentration of tyramine. found (fiµ:. 3). This degree of corrclation was not This was not true with respect to the "soluble" apparent for the "particulate" fraction (r = fraction. There was no apparent relationship 0.513). Somewhat different relationships were between concentration of tyramine in the presence observed in the ventricle. An excellent correlation of a fixed concentration of cocainc and dcgrces (r = 0.998) was found between the increasing of depletion of catecholamincs in either the lcvcls of catecholamines in the "particulate" "particulatc" or thc "soluble" fractions. fraction ancl the concentrations of cocainc in the A ctions of tyramine and cocaine on the ventric- 294 CAMPOS ET AL. Vol. 11¡ 1 ATRIA LEFT VENTRICLE CO NTROL TYRAMINE CONTROL TYRAMINE lµg/ml lµg/ml ·"'z ''°90 1 '.··..• SOLUBLE º~ i. PARTICULATE ....o: COARSE z w 70 u z o u w z 50 1 ~ <( } _J ' o I 30 - u w ~ u 10 0306090 306090 0~06090 306090 PERFUSION TIME IN MINUTE S l•' t<:. l. Changes in subcellubr concentrntions of catcchol:unines in thc isolatcd , perfused ca l hcart in thc absencc and presencc of tyrnrninc. Ali values a re exprcssed as a per cent of the mean conccntrntion found in nonpcrfuscd hea r(.s . to. ln dic:Ltes the value is siguificant ly diffe rent (P < .05 ) from t lmt of nonperfused hcarts. * Indicates lhc valuc is signi ficanUy differcnt (P < .05) from that for hcarts perfuscd for t he sarne period of time in ti.t e absence of drng. ATRIA LEFT VENTRICLE 130 COCAINE TYRAMINE COCAIN E TYRAM INE IJO "'z o .·.•.· SOLUBLE ¡::: PARTICULATE <( 90 i. ....o: COARSE z "'(.) 70 ~ 1í(.) "'z 5i 50 <( o_J V" "'.... 30 5 :. 'º ~ NP o 1 10 100 10 20 40 NP OtlOIOO 10 20 40 DRUG CONCENTRATION µg /ml Fra. 2. Effect.s of various conccntn Ltions of tyramine and cocaine on cat.ccholamine lcvels in Hn b cellular fractions of t hc isobted, pcrfused cat h()art.. All hearts, except cont rols (l\ !') , were pcrfused for 30 minutes . Ali values are exprcsscd as a per ceut of t he mean conccntration found in the nonperfuscd heart. * Indicates t hc valuc is signific .i ntly di !Ter ent (P < .05) from t hat for hcarts pcrfused with a solut ion containing no drug (O). 11 /a r rate. T yraminr. ( 1 µg / ml) markedly in (fig. 4). A greater positivc ehronotropic response c r ea~ ed cardiac ratc. This was greatest during was obtaincd with 1O µg / ml of tyramine, but thr. first 30 minute,_ , gra ATRIA LEFT VENTRICLE T YRAMIN[ 1 JIQ/rnl COCAINE 40.11 9 / rnl TYRAMINE 1_119 / ft'l l COCAI NE 40 .uottr1I 130 ~ p1u , COCAI NE c; h¡s TYR.1.M INE plut COC AIN E p!""' TYAA..-INE 11 0 ~ n SOLUBLE t;1 ~RTJ C\JL ATE n íl • COARSE'. l 90 ~ íl 1 nf'l 1 :UtlNP CP o 10 20 4() o 1 10 100 NP CP o 10 20 ~... o-- ~o ~. ~~10 ~100- ORUG CO NCENTRATION uq ! mi F11 :. :3 . The combined eflect.s of tyr:unine and cocainc at vnrious conccntrations on subcellular lcvcls of catcchohmincs in thc isolnted, pcrfused cat heart. Ali l1 P:t rts, except contrnls (.:\l'J, wcrc perfused for 30 minutes. Ali values are cxpresscd as a per cent of thc rncan cuncentrntion found in t l1 e nonpcrfuscd hcart. * Indiclltcs t.hc vahw is sig;nificaut. ly d if fercnt ( P < .05 ) from that for hearts perfuscd with a solution cont.aining; no drng (CP). ('Ol'ai11c at a t:oncentration of 10 µ g; / ml and thi .~ l\opin and Gor TABLE 3 Effects of cornbinations of tyrarnine and cocaine on concentrations of catecholarnines in subcellular fractions of the isolated cal heart 1 Catecholamine Concentrationª-µg/g of Fresh Tissue 1 Recovcry \Va ter N o. of Exp ts. 1 Perfuscd with (%) Content of Coarse i' Particulate Soluble 1 \Vhole 1 Tissue (%) fraction fraction fraction 1 homogenatc ¡ 1 A tria 5 N.P.b 0.38 0.34 0.87 1.44 110 72 ± 0.04 ± 0.05 ± 0.21 ± 0.42 ± 13.46 ± 15.67 5 K-Hc 0.26 0.29 0.60 1.47 79 84 ± 0.05 ± 0.03 ± 0.05 ± 0.07 ± 7.82 ± 1.19 6 Tyrarnine 1 µg/rnl 0.11 0.16 0.29 0.71 80 80 ± 0.02 ± 0.03 ± 0.03 ± 0.07 ± 6.35 ± 1.64 4 Tyrarnine 1 µg/rnl + 0.20 0.22 0.37 0.97 81 78 Cocaine 10 µg/rnl ± 0.05 ± 0.06 ± 0.09 ± 0.19 ± 10.47 ± 5.08 4 Tyrarnine 1 µg/ml + 0.24 0.23 0.44 1.12 81 77 Cocaine 20 µg/rnl ± 0.07 ± 0.04 ± 0.08 ± 0.18 ± 2.22 ± il. 75 3 Tyrarnine 1 µg/rnl + 0.25 0.33 0.65 1.44 85 77 Cocaine 40 µg/ml ± 0.08 ± 0.05 ± 0.10 ± 0.20 ± 0.91 ± 7.21 4 Cocaine 40 µg/rnl 0.42 0.50 0.86 l. 73 104 73 ± 0.07 ± 0.08 ± 0.19 ± 0.34 ± 0.65 ± 3.08 4 Cocaine 40 µg/ml + 0.Hi 0.20 0.47 0.87 93 77 Tyramine 10 µg/ml ± 0.03 ± 0.03 ± 0.11 ± 0.08 ± 9.95 ± 1.33 3 Cocaine 40 µg/ml + 0.22 0.21 0.35 0.85 92 79 Tyramine 100 µg/ml ± 0.05 ± 0.10 ± 0.07 ± 0.26 ± 4.04 ± 2.20 Left Ventricle 5 N.P. 0.66 0.76 0.66 1.61 128 78 ± 0.04 ± 0.08 ± 0.10 ± 0.08 ± 7.68 ± 0.58 5 K-H 0.43 0.65 0.42 1.57 96 81 ± 0.04 ± 0.07 ± 0.04 ± 0.13 ± 4.43 ± 0.88 6 Tyramine 1 µg/rnl 0.23 0.34 0.21 0.82 92 82 ± 0.03 ± 0.07 ± 0.03 ± 0.10 ± 5.86 ± 0.71 4 Tyrarnine 1 µg/rnl + 0.25 0.36 0.30 0.87 103 81 Cocaine 10 µg/rnl ± 0.01 ± 0.10 ± 0.07 ± 0.12 ± 7.45 ± 0.50 4 Tyramine 1 µg/rnl + 0.33 0.49 0.31 1.24 92 82 Cocaine 20 µg/ml ± 0.05 ± 0.09 ± 0.06 ± 0.14 ± 7.84 ± 0.87 3 Tyrarnine 1 µg/rnl + 0.47 0.80 0.52 1.89 96 8:1 Cocaine 40 µg/rnl ± 0.01 ± 0.09 ± 0.05 ± 0.09 ± 7.52 ± 4.00 4 Cocaine 40 µg/ml 0.64 1.15 0.79 2.51 114 82 ± 0.22 ± 0.16 ± 0.25 ± 0.80 ± 17.03 ± 0.96 4 Cocaine 40 µg/ml + 0.25 0.51 0.30 1.25 87 81 Tyramine 10 µg/rnl ± 0.09 ± 0.13 ± 0.09 ± 0.34 ± 11.47 ± 1.22 3 Cocaine 40 µg/ml + 0.30 0.45 0.35 0.92 120 83 Tyrarnine 100 µg/ml ± 0.04 ± 0.10 ± 0.04 ± 0.14 ± 5.61 ± 0.41 ª Calculated as norepinephrine and expressed as a mean ± S.E. b N.P. = Not perfused. Hearts were homogenized immediately after rernoval from the animal. e Krebs-Henseleit solution. of the rat (Pottcr et al., 1962) and dog (Chidsey demonstrating a depleting action in vivo arises et al., 1962), by tyraminc in the intact animal. from the fact that rate of replenishmcnt tends to High doses of tyramine had to be cmployed in kecp pace with ratc of release. Since there is no ali instances. Pcrhaps sorne of the difficulty in circulating supply of catecholamines m the 1963 TYRAMl:" 280 w 1-- z::J 240 ::;; Cf) 1-- Tyromint IOµ g(3 ) 5 10 15 20 25 30 5 10 15 20 25 30 PERFUSION TI ME (MINU TES) FIG. 4. Alterations in cardiac rate in the isolated, perfused cat hcart produced by various concentrn t ions of tyrnmine and cocainc singly and in combination. Figures in parenthcses indicatc tite number of individual values on which t he means are based. \ 'alues after each drug represent t ite conccntration (µg / ml) employed. i'olated perfuscd heart, lack of replenishment plausible in the light of in vitro studies on cate may account for the ease with which depletion cholamine-containing granules from thc adrcnal was produced. medulla (Hillarp, 1958) and isolated nerves (von The capacity of tyraminc to increasc the Euler and Lishajko, 1961). lf relcase from the output of catecholamines by the isolated heart "particulate" fraction prcdominated eme might has been demonstrated by Lindmar and expect a relative increase of the amines in the ?\foscholl (1961) and by Axelrod et al. (1962). "soluble" fraction, a situation observed whcn In the present work tyramine, in low concen depletion is produced by reserpine in the intact trations ( 1 µg/ ml), can induce dcpletion of dog (Campos ancl Shideman, 1962). This was catecholamines in the subcellular fractions of the not observed in the prcsent studies. Data support isolated cat heart. This is not in agreement with ing the hypothesis of a primary release from the :\asmyth's (1960) findings in the guinea-pig "soluble" fraction are provided by the study of heart. His inability to demonstrate de pletion thc effects of tyramine and cocaine, singly and mi ght have been due to interference by tyramine in combination, on amine leveb in the fractions with the biological assay for eatccholamines of the atria. While tyramine (1 µg/ ml) alone (Axelrod et al., J962) . Tyramine-induced deple produced a significant depletion in both ",.;olu ble" tion is signifi cant in both "solu ble" ami "particu and " particulate" fractions of atria after a 30- late" fractions of atria and lcft ventricle. This minute period of perfu ::;ion, cocaine (10 µg/ ml) rould mean that tyraminc releases catrcholamines causcd significant deplction only in the "soluble" from both fractions simultaneously or that fraction. Concomitant perfusion with tyramine depletion in the " particulate" fraction is second (1 µg/ ml) and cocaine (10 µg/ ml) effected ary to depletion in the "soluble" fraction. The significant depletion only in thc "soluble" second possibility would envision a movement of fraction. It is unlikely that this dcpletion rcsulted catccholamines from the "particulate" to the from an action of cocaine alone since this drug, " soluble" fraction once a ccrtain concentration cven in high concentrations, did not completely gradient has been established. This appears block the effect of 1 µg/ml of tyramine (fig. 3). 2!)8 CAMPOS ET AL. Vol . z,p It thu;; appears that cocainc rctard:; thc rate of biphasic action of cocaine that is do;,;c dcpc•ndcnt rclca"c induced by tyrnrninc. In thi,; rcspcct, also ha;: bcen ohservcd by Holtz et al. ( 1!HiO ). Lindmar ami l\Iusd10ll (lDG I) havc ,;hown that They found that low concrntration:-; potcntiatccl cocainc inhibits thc im·rc::k'C of thc output of and higher concrntrations antagonizcd the catreholarninc,; induecd by tyraminc in thc stimulatory a.ction of tyra.minc on isolatcd a.tria. isolatrd lwart. Thc rcsults of thc ;;tudic.-; on thc Fac.:ilitation of the release of catecholamine~ by int.eraetions of thc two drug.-; at gradcd closagc tyramine at low conceutrations of coeainc a.ne! leveb imlicate a goocl eorrclation bct.11·ce 11 change:; impairment of rdrase by this drug at higher in amiue lcvcb in thc ".-;olublc" fraction and eonccntrations cou ld explain thrse ohscrYatio1b. conccntrations of thc drugs. A comparable If the typc of obscrved re.'i ponse to coc:ain c corrclation in thc ea:-'c of thc "particulate" depend:; on the concentration or do"e employed, fraction 11·a~ not obscrved. This :otrongly ,;uggcsts then the data pre;:;ented here offcr an cxplanation that thc rcspofüe to tyraminc and cocaine are for the conf!icting findinl!i' hy some work<'r" primarily thc result of thcir actions on the (Axclrod et al., 1[)(32 ) that cocaine retards ancl by ",;nlublc'' fradion. other workers (\Yeiner ami Trendelenburg, 19G2) In th<:' left vcntricle, both tyraminc and coeainc that it does not alter the uptakc of exogcnous eau.-,;cd F< ignificant depletion in both fractions. cateeholamines. Schümann ancl \Veigmann (l !lfiO) There 1rns no correlation bet11·cen thc changcs of have suggested that cocaine acts on the ccll amine levP!s in the fractious and thc conccn rnernbrane since it does not prcvent tyramine tra.tions of drug:;. Perhaps the diffrrencc;; in thc induce PEN NEFATHER, J . N. AND RAND, M. J. : J . Physiol. SPECTOR , S., SJOEitllSMA, A., ZALTZMAN-NIREN 154: 277, 1960. BERG, P., LEVITT, M. A:-.iD UDENFRIENO, S .: PoTTE R, L. T. AND AxELROD, J.: Nature, Lond. Science 139: 1299, 1963. 194: 581, 1962. STROMBLAD, B. C. R.: Experientia 16: 417, 1960. PoT'rER, L., AxELRou, J. AND K oPIN, I. J. : Bio TAINTER, M. L . AND CHANG, D. K . : J . Pha rma col. chem. Pharmacol. 11: 254, 1962. 30: 193, 1927. ScHÜMANN, H. J . AND WEIGMANN, E.: Are h. exp. WEGMAN , A. AND KAKO, K.: Nature, Lond. 192: Path. Pha rma k . 240: 275, 1960. 978, 1961. SH ORE , P. A., COHN, v. H., JR., HIGH MAN, B. AND WEIL-MA1,HERBE, H . AND BoNE, A. D.: Nature, MALINO, H. M.: Nature, Lond. 181: 848, 1958. Lond. 180: 1050, 1957. SHORE, P. A. AND ÜLIN , J. S.: J. Pharmacol.122: WEINER, N. ANO TRENDELEN BURG, U.: J . Pha r 295, 1958. macol. 137: 56, 1962. SNEDECOR , G. W.: Statistical Methods, 5th ed., WHITBY, L. G., AXELROD, J . AND WEIL lowa State College Prcss, Ames, 1956. MALHERBE, H.: J . Pharmacol. 132: 193, 1961.