ENHANCED PHOTORELAXATION IN AORTA, PULMONARY-ARTERY AND CORPUS CAVERNOSUM PRODUCED BY BAY K-8644 OR N-NITRO-L-ARGININE

Segments of endothelium-denuded aorta, pulmonary arterial rings and strips of corpus cavernosum from rabbits were superfused with Krebs medium. Photorelaxation elicited by ultraviolet light (366 nm) was significantly enhanced by either BAY K 8644 (20 nM) or N-nitro-L-arginine (100 and 500 μM) and was associated with increased cyclic GMP. This action of both drugs was greater in pulmonary artery than aorta and corpus cavernosum and peristed in vascular rings for 90 min after drug removal. The effect was significantly attenuated by hemoglobin (10 μM) but was unaltered by superoxide dismutase (30 u/ml). The mechanism of such photosensitization is presently unclear. © 1992 Academic Press, Inc.