PARTICIPATION OF ENDOTHELIUM-DERIVED HYPERPOLARIZING FACTOR IN ACETYLCHOLINE-INDUCED RELAXATION OF THE ISOLATED RABBIT CORPUS CAVERNOSUM PENIS

The aim of this study was to determine the participation of endotheliu m-derived hyperpolarising factor (EDHF) in acetylcholine-induced relax ation of isolated rabbit corpus cavernosum penis (CCP). Acetylcholine relaxed noradrenaline-pre-contracted CCP in a concentration dependent manner. This relaxation was partially and concentration-dependently su ppressed by scorpion venom, which reduces acetylcholine-induced hyperp olarisation. Even in the presence of N-G-monomethyl-L-arginine as an i nhibitor of nitric oxide biosynthesis, scorpion venom further suppress ed the acetylcholine-induced relaxation. These results suggest that th e acetylcholine-induced relaxation of the rabbit CCP may result from t he production of EDHF as well as that of endothelium-derived relaxing factor.