Sensitivity of alpha-adrenoceptor agonists to the calcium channel activator, Bay K 8644, in canine saphenous vein. Pharmacology 1987;35(5):272-8
Date
01/01/1987Pubmed ID
2447595DOI
10.1159/000138320Scopus ID
2-s2.0-0023640980 (requires institutional sign-in at Scopus site) 2 CitationsAbstract
The purpose of the present study was to determine if the calcium channel activator, Bay K 8644, enhances the vasoconstrictor actions of selective alpha 1- and alpha 2-adrenoceptor agonists in canine saphenous vein. Phenylephrine (PE) and St 587 were used as fully and partially selective alpha 1-adrenoceptor agonists, B-HT 920 and B-HT 958 were used as fully and partially selective alpha 2-adrenoceptor agonists. Bay K 8644 (10(-8) M) markedly potentiated B-HT-958-mediated vasoconstrictor responses with a leftward shift and an increase in the maximum response of the logarithmic dose-response curve. Bay K 8644 produced less potentiation of responses to B-HT 920 and had minimal effects on responses to St 587 and PE. The intrinsic activities of the alpha-adrenoceptor agonists, as compared to the maximum response obtained by norepinephrine, in decreasing order, were PE greater than St 587 greater than B-HT 920 greater than B-HT 958, whereas the susceptibility of alpha-adrenoceptor agonists to potentiation by Bay K 8644 in decreasing order were B-HT 958 greater than B-HT 920 greater than St 587 greater than PE. These results suggest that Bay K 8644 preferentially improves the receptor-response coupling of alpha-adrenoceptor agonists with low intrinsic activity (alpha 2-agonists) versus agonists with high intrinsic activity (alpha-agonists) in canine saphenous vein.
Author List
Eskinder H, Gross GJMESH terms used to index this publication - Major topics in bold
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl esterAdrenergic alpha-Agonists
Animals
Azepines
Clonidine
Dogs
Female
In Vitro Techniques
Ion Channels
Male
Muscle, Smooth, Vascular
Saphenous Vein
