Skip to main content
NCBI home page
British Journal of Pharmacology logoLink to British Journal of Pharmacology
. 1989 May;97(1):222–228. doi: 10.1111/j.1476-5381.1989.tb11945.x

Characterization of pigment aggregating alpha 2-adrenoceptors of fish melanophores by use of different agonists after partial irreversible receptor inactivation.

J O Karlsson 1, R G Andersson 1, N Grundström 1
PMCID: PMC1854472  PMID: 2566352

Abstract

1. The affinity for, and the intrinsic efficacy on, postsynaptic melanosome aggregating alpha 2-adrenoceptors of fish melanophores was studied for B-HT 920, clonidine, medetomidine, noradrenaline, phenylephrine and UK-14,304. Investigations were carried out by evaluating the effects of progressive, irreversible inactivation of the alpha 2-adrenoceptors by benextramine. 2. The double reciprocal plots of equieffective concentrations of B-HT 920, clonidine, noradrenaline and phenylephrine were linear, which indicated that these compounds exerted their effects, mainly, through interaction with one receptor site. 3. The affinity for the alpha 2-adrenoceptor selective agonist B-HT 920, was found to be about 1000 times higher than the affinity for the alpha 1-adrenoceptor selective agonist phenylephrine. 4. The corresponding plot of equieffective concentrations of medetomidine was not linear, which may indicate that this imidazole compound exerted its effect through more than one receptor site. However, when phenoxybenzamine was used in place of the more selective benextramine, a linear relationship was obtained.

Full text

PDF
222

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Andersson R. G., Karlsson J. O., Grundström N. Adrenergic nerves and the alpha 2-adrenoceptor system regulating melanosome aggregation within fish melanophores. Acta Physiol Scand. 1984 Jun;121(2):173–179. doi: 10.1111/j.1748-1716.1984.tb07444.x. [DOI] [PubMed] [Google Scholar]
  2. Berthelsen S., Pettinger W. A. A functional basis for classification of alpha-adrenergic receptors. Life Sci. 1977 Sep 1;21(5):595–606. doi: 10.1016/0024-3205(77)90066-2. [DOI] [PubMed] [Google Scholar]
  3. Karlsson J. O., Andersson R. G., Elwing H., Grundström N. Comparative studies on nerve- and noradrenaline-induced melanosome aggregation within different species of fish. Comp Biochem Physiol C. 1987;88(2):287–291. doi: 10.1016/0742-8413(87)90123-x. [DOI] [PubMed] [Google Scholar]
  4. Karlsson J. O., Elwing H., Grundström N., Andersson R. G. Pronounced supersensitivity of postjunctional alpha adrenoceptors after denervation of fish melanophores. J Pharmacol Exp Ther. 1988 Jul;246(1):345–351. [PubMed] [Google Scholar]
  5. Karlsson J. O., Grundström N., Wikberg J. E., Friedman R., Andersson R. G. The effect of pertussis toxin on alpha-2-adrenoceptor-mediated pigment migration in fish melanophores. Life Sci. 1985 Sep 16;37(11):1043–1049. doi: 10.1016/0024-3205(85)90595-8. [DOI] [PubMed] [Google Scholar]
  6. Langer S. Z. Presynaptic regulation of catecholamine release. Biochem Pharmacol. 1974 Jul 1;23(13):1793–1800. doi: 10.1016/0006-2952(74)90187-7. [DOI] [PubMed] [Google Scholar]
  7. Limbird L. E. Receptors linked to inhibition of adenylate cyclase: additional signaling mechanisms. FASEB J. 1988 Aug;2(11):2686–2695. doi: 10.1096/fasebj.2.11.2840317. [DOI] [PubMed] [Google Scholar]
  8. Morishita F. Responses of the melanophores of the medaka, Oryzias latipes, to adrenergic drugs: evidence for involvement of alpha 2 adrenergic receptors mediating melanin aggregation. Comp Biochem Physiol C. 1987;88(1):69–74. [PubMed] [Google Scholar]
  9. Mottram D. R. Pharmacological evidence for high affinity and low affinity a2-adrenoceptor binding sites in rat vas deferens. Arch Int Pharmacodyn Ther. 1983 Jul;264(1):28–39. [PubMed] [Google Scholar]
  10. Mottram D. R. Pre-junctional alpha 2-adrenoceptor activity of B-HT920. J Pharm Pharmacol. 1983 Oct;35(10):652–655. doi: 10.1111/j.2042-7158.1983.tb02859.x. [DOI] [PubMed] [Google Scholar]
  11. Mottram D. R., Thakar Y. The action and interaction of beta-phenethylamines and imidazolines on prejunctional alpha 2-adrenoceptors of guinea-pig ileum in the presence of the non-competitive antagonist benextramine. J Pharm Pharmacol. 1984 Oct;36(10):668–672. doi: 10.1111/j.2042-7158.1984.tb04840.x. [DOI] [PubMed] [Google Scholar]
  12. Nichols A. J., Ruffolo R. R., Jr The relationship of alpha-adrenoceptor reserve and agonist intrinsic efficacy to calcium utilization in the vasculature. Trends Pharmacol Sci. 1988 Jul;9(7):236–241. doi: 10.1016/0165-6147(88)90152-6. [DOI] [PubMed] [Google Scholar]
  13. Nilsson S. Adrenergic innervation and drug responses of the oval sphincter in the swimbladder of the cod (Gadus morhua). Acta Physiol Scand. 1971 Dec;83(4):446–453. doi: 10.1111/j.1748-1716.1971.tb05102.x. [DOI] [PubMed] [Google Scholar]
  14. Parker R. B., Waud D. R. Pharmacological estimation of drug-receptor dissociation constants. Statistical evaluation. I. Agonists. J Pharmacol Exp Ther. 1971 Apr;177(1):1–12. [PubMed] [Google Scholar]
  15. Ruffolo R. R., Jr Review important concepts of receptor theory. J Auton Pharmacol. 1982 Dec;2(4):277–295. doi: 10.1111/j.1474-8673.1982.tb00520.x. [DOI] [PubMed] [Google Scholar]
  16. Ruffolo R. R., Jr alpha-Adrenoceptors. Monogr Neural Sci. 1984;10:224–252. [PubMed] [Google Scholar]
  17. Ruffolo R. R., Turowski B. S., Patil P. N. Lack of cross-desensitization between structurally dissimilar alpha-adrenoceptor agonists. J Pharm Pharmacol. 1977 Jun;29(6):378–380. doi: 10.1111/j.2042-7158.1977.tb11344.x. [DOI] [PubMed] [Google Scholar]
  18. Savola J. M., Ruskoaho H., Puurunen J., Salonen J. S., Kärki N. T. Evidence for medetomidine as a selective and potent agonist at alpha 2-adrenoreceptors. J Auton Pharmacol. 1986 Dec;6(4):275–284. doi: 10.1111/j.1474-8673.1986.tb00654.x. [DOI] [PubMed] [Google Scholar]
  19. Starke K., Endo T., Taube H. D. Relative pre- and postsynaptic potencies of alpha-adrenoceptor agonists in the rabbit pulmonary artery. Naunyn Schmiedebergs Arch Pharmacol. 1975;291(1):55–78. doi: 10.1007/BF00510821. [DOI] [PubMed] [Google Scholar]
  20. Vizi E. S., Ludvig N., Rónai A. Z., Folly G. Dissociation of presynaptic alpha 2-adrenoceptors following prazosin administration: presynaptic effect of prazosin. Eur J Pharmacol. 1983 Nov 25;95(3-4):287–290. doi: 10.1016/0014-2999(83)90648-9. [DOI] [PubMed] [Google Scholar]
  21. Wikberg J. E. Pharmacological classification of adrenergic alpha receptors in the guinea pig. Nature. 1978 May 11;273(5658):164–166. doi: 10.1038/273164a0. [DOI] [PubMed] [Google Scholar]

Articles from British Journal of Pharmacology are provided here courtesy of The British Pharmacological Society

RESOURCES