Dihydropyridine Ca2+ channel agonists and antagonists potentiate ultraviolet light-induced relaxation through cyclic GMP formation in porcine coronary artery.
We investigated the mechanisms of dihydropyridine Ca2+ channel agonist potentiation of ultraviolet (UV) light-induced smooth muscle relaxation in porcine coronary artery rings. Rings contracted with the dihydropyridine Ca2+ channel agonist, (+)-S-202-791, were more sensitive to relaxation in response to UV light than were rings contracted with KCl or histamine. Relaxation of (+)-S-202-791-contracted rings was independent of the presence of endothelium and was associated with cyclic GMP formation. Methylene blue (MB) prevented UV light-induced relaxation and cyclic GMP formation. UV light-induced relaxation of histamine and KCl contracted rings and cyclic GMP formation were potentiated by (+)-S-202-791 or the Ca2+ channel antagonist, (-)-R-202-791. Exposure of (+)-S-202-791 to UV light decreased its contractile potency. The data suggest that UV light-induced relaxation of vascular smooth muscle (VSM) is mediated through cyclic GMP formation and that potentiation of UV light-induced relaxation by dihydropyridine Ca2+ channel agonists results from their breakdown to a compound(s) that activates guanylate cyclase.
Baik
Y H
YH
Department of Pharmacology and Cell Biophysics, University of Cincinnati, College of Medicine 45267-0575.
French
J F
JF
Schwartz
A
A
Rapoport
R M
RM
D000818:Animals; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D004095:Dihydropyridines / Q000494:pharmacology*; D066298:In Vitro Techniques; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D013237:Stereoisomerism; D013552:Swine; D014466:Ultraviolet Rays
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D004095:Dihydropyridines; C045796:SAN 202791; D006152:Cyclic GMP