Effects of ultraviolet radiation on the tension and the cyclic GMP level of bovine mesenteric arteries

Abstract

Strips of bovine mesenteric arteries brought to sustained contraction by the addition of 3.0 microM phenylephrine relaxed when exposed to ultraviolet radiation (366 nm). The relaxation was reversible and associated with a rapid increase in the cGMP content. After termination of the radiation the cGMP level rapidly decreased below the basal level. The crude soluble guanylate cyclase from the artery was stimulated about 8-fold by ultraviolet radiation (366 nm). Neither the cGMP-phosphodiesterase activity nor the cAMP level were found to be changed during irradiation. The ultraviolet light-induced relaxation was not dependent on an intact intimal surface. Furthermore, the relaxing effect was found to be enhanced and accompanied by a larger increase of the cGMP level in nitroglycerin-tolerant arteries. The present results show that the ultraviolet light-induced relaxation in bovine mesenteric arteries is associated with a rapid increase in the cGMP content and that ultraviolet light and nitrocompounds may exert their relaxing actions through a common substance.