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8-Bromo cyclic guanosine monophosphate mimics the actions of nitroglycerin on alpha-adrenergic mechanisms in canine saphenous vein. Pharmacology 1987;35(1):16-23

Date

01/01/1987

Pubmed ID

2819902

DOI

10.1159/000138291

Scopus ID

2-s2.0-0023201952 (requires institutional sign-in at Scopus site)   1 Citation

Abstract

The purpose of the present study was to determine if 8-bromo cyclic guanosine monophosphate (cGMP) mimics the actions of nitroglycerin in inhibiting alpha 1- versus alpha 2-mediated constrictor responses in vitro using rings prepared from isolated canine saphenous vein. Contractions were produced by phenylephrine, a selective alpha 1-adrenoceptor agonist and B-HT 920, a selective alpha 2-adrenoceptor agonist. The inhibitory effects of nitroglycerin and 8-bromo cGMP on contractions produced by submaximal concentrations (EC75) of phenylephrine and B-HT 920 were determined. 8-Bromo cGMP like nitroglycerin produced a selective antagonism of alpha 2-adrenoceptor-mediated responses and had minimal effects on alpha 1-adrenoceptor-induced constriction. However, after removal of spare postsynaptic vascular alpha 1-adrenoceptors by treatment with the irreversible alpha-adrenoceptor antagonist phenoxybenzamine (5 X 10(-8) M, 1 X 10(-7) M), the alpha 1-adrenoceptor-mediated vasoconstrictor responses of phenylephrine became highly sensitive to antagonism by 8-bromo cGMP and nitroglycerin. These data suggest that the action of 8-bromo cGMP like nitroglycerin is 'buffered' by the presence of a large alpha 1-adrenoceptor reserve in canine saphenous vein. The similarity in the efficacy and potency of these two agents suggests that the effects of nitroglycerin in canine saphenous vein may be the result of an increase in intracellular cGMP.

Author List

Eskinder H, Gross GJ

MESH terms used to index this publication - Major topics in bold

Animals
Azepines
Calcium
Cyclic GMP
Dogs
Dose-Response Relationship, Drug
Female
In Vitro Techniques
Male
Nitroglycerin
Nitroprusside
Phenylephrine
Receptors, Adrenergic, alpha
Saphenous Vein
Vasodilation