8-Bromo cyclic GMP mimics the actions of nitroglycerin in modulating responses produced by full and partial alpha-adrenoceptor agonists in canine saphenous vein. Eur Heart J 1988 Jan;9 Suppl A:11-5
Date
01/01/1988Pubmed ID
2900765DOI
10.1093/eurheartj/9.suppl_a.11Scopus ID
2-s2.0-0023923137 (requires institutional sign-in at Scopus site)Abstract
The purpose of the present study was to determine whether 8-bromo cyclic GMP (8-Br cGMP) mimics the actions of nitroglycerin (GTN) in inhibiting alpha-1 versus alpha-2 adrenoceptor-mediated constrictor responses in canine saphenous vein. Phenylephrine (PE) and L-dobutamine were used as full and partial alpha-1 adrenoceptor agonists, respectively, and B-HT 920 was employed as a selective alpha-2 adrenoceptor agonist. The ability of 8-Br cGMP and GTN to inhibit vasoconstrictor responses to a standard agonist concentration of PE, L-dobutamine and B-HT 920 was determined. 8-Br cGMP like GTN produced a selective antagonism of alpha-2-mediated responses of B-HT 920 and had minimal effects on alpha-1-induced constrictor responses of phenylephrine. However, when a portion of the alpha-1-adrenoceptor pool was inactivated by phenoxybenzamine (POB) (5 x 10(-8) M, 1 x 10(-7) M) 8-Br cGMP like GTN produced a significant depression of responses to PE. In addition, contractions produced by L-dobutamine, a selective partial alpha-1 adrenoceptor agonist (no alpha receptor reserve), were highly sensitive to inhibition by 8-Br cGMP and GTN. These results suggest that the presence of a large alpha-1-adrenoceptor reserve to PE concealed an underlying functional antagonism to alpha-1-adrenoceptor-mediated responses by GTN and 8-Br cGMP. The similarity in the efficacy and potency of these two agents (8-Br cGMP and GTN) suggests that the effects of GTN in canine saphenous vein may be the result of an increase in the intracellular concentration of cGMP.
Author List
Eskinder H, Gross GJMESH terms used to index this publication - Major topics in bold
Adrenergic alpha-AgonistsAnimals
Cyclic GMP
Dobutamine
Dogs
In Vitro Techniques
Nitroglycerin
Phenylephrine
Saphenous Vein
Vasoconstriction
Vasodilation
