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. 1988 Aug;94(4):1085–1090. doi: 10.1111/j.1476-5381.1988.tb11626.x

Evidence that the population of postjunctional-adrenoceptors mediating contraction of smooth muscle in the rabbit isolated ear vein is predominantly alpha 2.

C J Daly 1, J C McGrath 1, V G Wilson 1
PMCID: PMC1854110  PMID: 2905182

Abstract

1. Noradrenaline (NA), phenylephrine and UK-14304 elicited concentration-dependent contractions of the rabbit isolated ear vein of similar maximal magnitude. The rank order of potency, UK-14304 greater than noradrenaline greater than phenylephrine, is consistent with that of an effect mediated through an alpha 2-subtype. 2. The potent and highly selective alpha 1-adrenoceptor antagonists prazosin and YM-12617, at concentrations as high as 1 microM, produced less than a 4 fold rightward displacement of the NA concentration-response curve. 3. The selective alpha 2-adrenoceptor antagonists rauwolscine, Wy-26703 and CH-38083 antagonized responses to noradrenaline in a competitive manner. For all three antagonists, the pA2 values were consistent with an effect at alpha 2-adrenoceptors. However, 0.1 microM YM-12617 increased the potency of rauwolscine 2 fold indicating the presence of a small population of postjunctional alpha 1-adrenoceptors. 4. The relative antagonist potency of the yohimbine diastereoisomers rauwolscine and corynanthine against noradrenaline (rauwolscine 30 fold greater than corynanthine) is also consistent with an effect at alpha 2-adrenoceptors. 5. Contractions elicited by noradrenaline in the rabbit isolated ear vein appear to be mediated predominantly by postjunctional alpha 2-adrenoceptors.

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Selected References

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  1. ARUNLAKSHANA O., SCHILD H. O. Some quantitative uses of drug antagonists. Br J Pharmacol Chemother. 1959 Mar;14(1):48–58. doi: 10.1111/j.1476-5381.1959.tb00928.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Abramovich D. R., Page K. R., Parkin A. M. The effect of prostaglandin D2 on the blood vessels of the perfused isolated cotyledon of the human placenta. Br J Pharmacol. 1984 Jan;81(1):19–21. doi: 10.1111/j.1476-5381.1984.tb10737.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Alabaster V. A., Keir R. F., Peters C. J. Comparison of activity of alpha-adrenoceptor agonists and antagonists in dog and rabbit saphenous vein. Naunyn Schmiedebergs Arch Pharmacol. 1985 Jul;330(1):33–36. doi: 10.1007/BF00586706. [DOI] [PubMed] [Google Scholar]
  4. Bou J., Massingham R. Effect of diltiazem upon contractile responses to phenylephrine, cirazoline, Sgd 101/75, St 587 and B-HT 920 in rabbit aorta and dog saphenous vein preparations. Eur J Pharmacol. 1986 Mar 4;121(3):319–325. doi: 10.1016/0014-2999(86)90252-9. [DOI] [PubMed] [Google Scholar]
  5. Cambridge D. UK-14,304, a potent and selective alpha2-agonist for the characterisation of alpha-adrenoceptor subtypes. Eur J Pharmacol. 1981 Jul 10;72(4):413–415. doi: 10.1016/0014-2999(81)90588-4. [DOI] [PubMed] [Google Scholar]
  6. Cheung D. W. An electrophysiological study of alpha-adrenoceptor mediated excitation-contraction coupling in the smooth muscle cells of the rat saphenous vein. Br J Pharmacol. 1985 Jan;84(1):265–271. [PMC free article] [PubMed] [Google Scholar]
  7. Constantine J. W., Lebel W., Archer R. Functional postsynaptic alpha 2- but not alpha 1-adrenoceptors in dog saphenous vein exposed to phenoxybenzamine. Eur J Pharmacol. 1982 Dec 3;85(3-4):325–329. doi: 10.1016/0014-2999(82)90219-9. [DOI] [PubMed] [Google Scholar]
  8. Docherty J. R., Constantine J. W., Starke K. Smooth muscle of rabbit aorta contains alpha 1-but not alpha 2-adrenoceptors. Naunyn Schmiedebergs Arch Pharmacol. 1981 Aug;317(1):5–7. doi: 10.1007/BF00506248. [DOI] [PubMed] [Google Scholar]
  9. Flavahan N. A., Vanhoutte P. M. Alpha-1 and alpha-2 adrenoceptor: response coupling in canine saphenous and femoral veins. J Pharmacol Exp Ther. 1986 Jul;238(1):131–138. [PubMed] [Google Scholar]
  10. Hicks P. E., Langer S. Z., Macrae A. D. Differential blocking actions of idazoxan against the inhibitory effects of 6-fluoronoradrenaline and clonidine in the rat vas deferens. Br J Pharmacol. 1985 Sep;86(1):141–150. doi: 10.1111/j.1476-5381.1985.tb09444.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Hinzen D., Hornykiewicz O., Kobinger W., Pichler L., Pifl C., Schingnitz G. The dopamine autoreceptor agonist B-HT 920 stimulates denervated postsynaptic brain dopamine receptors in rodent and primate models of Parkinson's disease: a novel approach to treatment. Eur J Pharmacol. 1986 Nov 12;131(1):75–86. doi: 10.1016/0014-2999(86)90517-0. [DOI] [PubMed] [Google Scholar]
  12. Honda K., Takenaka T., Miyata-Osawa A., Terai M., Shiono K. Studies on YM-12617: a selective and potent antagonist of postsynaptic alpha 1-adrenoceptors. Naunyn Schmiedebergs Arch Pharmacol. 1985 Jan;328(3):264–272. doi: 10.1007/BF00515552. [DOI] [PubMed] [Google Scholar]
  13. Hooker C. S., Calkins P. J., Fleisch J. H. On the measurement of vascular and respiratory smooth muscle responses in vitro. Blood Vessels. 1977;14(1):1–11. doi: 10.1159/000158110. [DOI] [PubMed] [Google Scholar]
  14. Langer S. Z., Dubocovich M. L. Cocaine and amphetamine antagonize the decrease of noradrenergic neurotransmission elicited by oxymetazoline but potentiate the inhibition by alpha-methylnorepinephrine in the perfused cat spleen. J Pharmacol Exp Ther. 1981 Jan;216(1):162–171. [PubMed] [Google Scholar]
  15. Lattimer N., McAdams R. P., Rhodes K. F., Sharma S., Turner S. J., Waterfall J. F. Alpha 2-adrenoceptor antagonism and other pharmacological antagonist properties of some substituted benzoquinolizines and yohimbine in vitro. Naunyn Schmiedebergs Arch Pharmacol. 1984 Oct;327(4):312–318. doi: 10.1007/BF00506242. [DOI] [PubMed] [Google Scholar]
  16. McGrath J. C. Evidence for more than one type of post-junctional alpha-adrenoceptor. Biochem Pharmacol. 1982 Feb 15;31(4):467–484. doi: 10.1016/0006-2952(82)90147-2. [DOI] [PubMed] [Google Scholar]
  17. Schümann H. J., Lues I. Postjunctional alpha-adrenoceptors in the isolated saphenous vein of the rabbit. Characterization and influence of angiotensin. Naunyn Schmiedebergs Arch Pharmacol. 1983 Aug;323(4):328–334. doi: 10.1007/BF00512471. [DOI] [PubMed] [Google Scholar]
  18. Takayanagi I., Konno F., Toru T., Takahashi R. Difference in mode of action of alpha 1-adrenoceptor antagonists on some vascular smooth muscles and efficacy. Jpn J Pharmacol. 1986 Oct;42(2):237–241. doi: 10.1254/jjp.42.237. [DOI] [PubMed] [Google Scholar]
  19. VAN ROSSUM J. M. Cumulative dose-response curves. II. Technique for the making of dose-response curves in isolated organs and the evaluation of drug parameters. Arch Int Pharmacodyn Ther. 1963;143:299–330. [PubMed] [Google Scholar]
  20. Vizi E. S., Harsing L. G., Jr, Gaal J., Kapocsi J., Bernath S., Somogyi G. T. CH-38083, a selective, potent antagonist of alpha-2 adrenoceptors. J Pharmacol Exp Ther. 1986 Aug;238(2):701–706. [PubMed] [Google Scholar]

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