NON-SYNERGISTIC RELAXANT EFFECTS OF VASOACTIVE INTESTINAL POLYPEPTIDEAND SIN-1 IN HUMAN ISOLATED CAVERNOUS ARTERY AND CORPUS CAVERNOSUM

Since vasoactive intestinal peptide (VIP) and nitric oxide (NO) are co nsidered to be non-adrenergic, non-cholinergic (NANC) inhibitory media tors in human penile erectile tissue, the goal of this study was to di scover possible synergistic effects of exogeneous VIP and the NO donor 3-morpholino-sydnonimine (SIN-1) in human isolated cavernous arteries and cavernosal smooth muscle. In contrast to VIP, SIN-1 elicited comp lete and reproducible relaxant actions. Combined administration of VIP and SIN-1 revealed non-synergistic, independent relaxant effects in b oth investigated tissues. The results do not favour a combined adminis tration of VIP and SIN-1 as a new therapeutic approach in the treatmen t of erectile dysfunction.