MODE OF ACTION OF CORONARY ARTERIAL RELAXATION BY PROSTACYCLIN

Abstract

A close association is suggested between the relaxing actions of PGI2 and its increasing effects on cAMP levels in bovine coronary smooth muscle; evidence indicative of a transmitter function of cAMP in PGI2-induced relaxation is presented. In time course experiments in circular strips of bovine coronary arteries the increase in cAMP levels caused by PGI2 preceded the mechanical response. The relaxant and cAMP increasing effects produced by PGI2 were significantly potentiated by the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine. In a particulate preparation of bovine coronary arteries PGI2 concentration dependently stimulated adenylate cyclase in the presence of GTP.