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https://theses.gla.ac.uk/ Theses Digitisation: https://www.gla.ac.uk/myglasgow/research/enlighten/theses/digitisation/ This is a digitised version of the original print thesis. Copyright and moral rights for this work are retained by the author A copy can be downloaded for personal non-commercial research or study, without prior permission or charge This work cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Enlighten: Theses https://theses.gla.ac.uk/ [email protected] The contractility of the portal vein: role of oxygen and calcium. A thesis presented for the degree of Doctor of Philosophy. BY OLUFUNMILAYO ABOSEDE FASEHUN INSTITUTE OF PHYSIOLOGY, UNIVERSITY OF GLASGOW. OCTOBER 1987 ProQuest Number: 10997347 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 10997347 Published by ProQuest LLC(2018). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 TABLE q f contents Page No List of figures ............................... (i) List of tables .............................. (vi) Acknowledgements............................... (vii) Declaration..................................... (ix) Summary..........................................(xi) Chapter 1 Literature xevie# The role of O2 in the contractility of vascular smooth muscle ...................... 1 The role of calcium in vascular contractility................................... 16 A l m a Q.L tLa .study............................53 Chapter 2^ Influence at axy.g.en o n the nanzatlmulated spontaneous activity and drug induced effects at tha EE Y S u m m a r y ....................................... 55 Introduction...................................... 56 M e t h o d s ....................................... 57 R e s u l t s ........................................64 Discussion........................ 84 Chapter 3^ Alpha- adrenoceptors and agonists and £a— dependence of the RPV Summary........................................... 95 Introduction...................................... 96 Methods........................................... 98 Results.......................................... 101 Discussion....................................... 110 Chapter A*. Effects at Bay K 8644 an .the RPV Summary.......................................... 119 Introduction..................................... 120 Methods ....................................... 121 Results........................ •................. 124 Discussion....................................... 130 Chapter 5. Assay at Bay K 8644 at different O2 tensions. Summary.............. 138 Introduction............................. 139 Methods ...................................... 139 Results..................... C............. 141 Discussion....................................... 153 Chapter fL_ Modulatory affects a£ hypoxia an fa— channel function. Summary........................ 160 Introduction..................................... 160 Methods...........................................162 Results...........................................166 Discussion....................................... 175 Chapter 7 £a— modulators and hypoxic vasodilatation. Summary.......................................... 185 Introduction..................................... 186 M e t h o d s ....................................... 187 Results...........................................191 Discussion....................................... 198 General discussion and conclusions............... 208 Appendix. I. EGTA and NTA buffers Theoretical explanation for the buffers........ 212 Recipe for the Ca2+ buffers .................. 212 II. Measurement of bath P02................... 213 References.............. — .. .214 LIST QF FIGURES. Chapter L*. Fig 1.1. The chemical structures of Ca^+ agonists and Ca antagonists used in the study.. Chapter 2. Fig 2.1 The tissue bath and the parameters of RPV responses measured. Fxg 2.2. Effect of propranolol or cocaine on NA concentration response relationship at 95%C>2 and 16%C>2 in the RPV. Fig 2.3. Effect of various combinations of EDTA, cocaine and propranolol on NA concentration response relationship at 95%02 and 16%02 in the RPV (change in height of response measurements. Fig 2.4. Effect of various combinations of EDTA, cocaine and propranolol on NA concentration response relationship at 95%C>2 and 16%C>2 (change in baseline tension measurements). Fig 2.5. The response induced by NA without or with infusion at 95%C>2 and 16%02 in the RPV and the rat anococcygeus muscle. Fi.g 2.6. Time course of RPV response to NA luM at different C>2 tensions at a chart speed of lOmm/min. Fig 2.7. RPV response to different concentrations of NA at different C>2 tensions at 15s and 5min. Fig 2.8. Time course of RPV response to NA at different C>2 tensions at a fast chart speed of 50mm/rain. FjL.g 2.9. Representative traces of response to amidephrine, phenylephrine, UK14304 and xylazine. Fig 2.10. Concentration response curves to various agonists expressed as percentage of the maximum response to NA at 16%02. Fig 2.11. Schematic representation of the pattern of responses induced by various agonists in the RPV and the susceptibility of such responses to 02- Fig 2.12. The schild plot for prazosin against NA at 16 % O2 . Fig 2.13. The schild plot for prazosin against UK14304 at 16%C>2 . Fig 2.14. UK14304 and xylazine-induced effects in the presence of a mildly depolarizing KC1. (i) FJLg 2.15. Representative traces of effect of ouabain on the biphasic response to NA at 16%02. .E-iS 2.16. Representative traces for KC1 induced responses without and with either choline or NaCl at 16%02 . Fig 2.17. Representative trace of contraction induced by caffeine 20mM in RPV. Chapter 1 Fig 3.1. The response of the non-stimulated rat portal vein to Ca cumulative re-addition from unbuffered and EGTA and NTA buffered [Ca ] = zero. Fig 3.2. Effect of time of incubation on subsequent response of RPV to unbuffered Ca cumulative re addition at either 16%02 or 95%02. Fig 3.3. The response of RPV to either Ca^+ cumulative or non-cumulative re-addition in buffered Ca . Fig 3.4. The response of RPV to Ca^+ cumulative re addition when the tissues are stimulated with NA in unbuffered and buffered Ca . Fig. 3.5. Time course of RPV responses to NA 0.3juM various Ca levels (unbuffered and buffered) zero, 0.31, 0.63 , 1.25 and 2.5mM Ca in the RPV. Also shown is the comparison with the rat anococcygeus. Fig 3.6. The effects of Bay K 8644 on the spontaneous activity and NA stimulated RPV during Ca2+ re-addition in unbuffered Ca2+. Fig 3.7. Effect of Bay K 0.3pM on NA stimulated RPV during Ca^+ cumulative re-addition in buffers. Fig 3.8. Response of the RPV to Ca^+ cumulative re addition when the tissues are stimulated with (a) NA luM and (b) amidephrine lpM in buffered Ca . Pig 3.9. The response of RPV to Ca2+ cumulative re addition when the tissues are.stimulated with UK14304 lOuM and xylazine lOuM and lOOuM in buffered Ca . .Chapter Fig 4.1. The effect of increasing concentrations of Bay K on the spontaneous activity of RPV at 2.5mM Ca at 95%02. Fig 4.2. Bay K 8644 concentration/ response in tissues contracted with NA 0.3pM at 2.5mM Ca at 95%02. (ii) FJLg 4.3. Bay K concentration/ response in tissues contracted with NA at 2.5mM Ca2+ at 16%02. F±a 4.4. Bay K concentration/ response in tissues contracted with NA luM at 2.5mM Ca2+ at 4%C>2. Fig 4.5. Bay K concentration/ response in tissues contracted with KC1 50mM at 2.5mM Ca2' + at 95% 02, 16%C>2 and 4%02« ZJLa 4.6. Effects of Bay K 86 44 0.3pM on the RPV response to NA 0.3pM in varying unbuffered [Ca2+]Q (non- cumulative) at 16%02 and 95%02. Fig 4.7. The effect of Bay K 8644 on the Ca2 + response of the portal vein in KC1 50mM -depolarized tissue during Ca2+ cumulative re-addition from unbuffered zero Ca Krebs at 16%C>2 and 95%02. Fig 4.8. The effects of Bay K 8644 0.3uM on the Ca2 + response of the portal vein in KC1 50mM depolarized tissues during unbuffered Ca2+ cumulative re-addition at 16%C>2 and 95%C>2. Chapter 5. Fig 5.1. Bay K concentration/ relationship in KC1 50 mM contracted tissues at 0.31mM Ca in different O2 tensions. Fig 5.2. Effect of decreasing O2 tension on tlxe control response to KC1 50mM and NA 0.3pM at 0.31mM Ca2 . Fig 5.3. Bay K concentration/ relationship in NA 0.3pM contracted tissues at 0.31mM Ca in different O2 tensions. Fig 5.4. Time matched control response to KC1 50mM at 0.31mM Ca at 95%02 and 16%02. Fig 5.5. Bay K 8644 concentration/ response relationship in KC1 50mM contracted RPV at different concentrations of buffered Ca at 16%02* Fig 5.6. Concentration response relationship for Bay K and CGP 28392 in NA 0.3pM contracted tissues at 16%0o. Fig 5.7. CGP 28392 concentration response relationship in KC1 50mM contracted tissues at I6O2 and 0%C>2. Fig 5.8. Concentration response relationship for Bay K 8644 and CGP 28392 in KC1 50mM contracted tissues at hypoxia (0%O2). Fig 5.9. CGP 2893 concentration response relationship at at buffered Ca level 0.31mM at 95%C>2. Fig 5.10. Concentration / response relationship for Bay K and CGP 28392 in NA 0.3uM contracted tissues at 16 % C>2 . (iii) Fig 5.11. Nifedipine's interaction with Bay K 8644 induced effects. .Chapter 6. F±.g The [Ca2 + ]/ response relationship in RPV contracted with KC1 50mM during non-cumulative Ca re addition in hypoxia (0%O2) and 16%02 (normoxia).