The Effects of Vasopressin and Desmopressin on the Contractile and Relaxation Responses of Rabbit Cavernosal Smooth Muscle

Abstract

Purpose: This study aimed to investigate the effects of vasopressin and desmopressin on the contractile and relaxative responses of rabbit cavernosal smooth muscle. Materials and Methods: Isometric tension studies were conducted to investigate the effects of vasopressin (10−14-10−8M) and desmopressin (10−1410−8M) on the contraction and relaxation responses of rabbits cavernous muscle strips in an organ bath. The effects of pretreatment with phenylephrine (10−5M), L-NAME (10−5M) and indomethacin (10−5M) on the contraction and relaxation responses of the vasopressin and desmopressin were also investigated. The statistics were analyzed by Student's t-test and ANOVA. Results: Vasopressin contracted the strips in a dose-dependent manner, while desmopressin did not. The phenylephrine-induced contraction was dose-dependently increased by vasopressin, but it was dose-dependently relaxed by desmopressin. L-NAME pre-treatment did not block the relaxation response, but indomethacin pre-treatment did. Vasopressininduced contraction occurred the via V1 receptor, while desmopressininduced relaxation occurred via the V2 receptor. Conclusions: Vasopressin, in pathophysiological circumstances, would worsen erectile dysfunction. On the contrary, desmopressin, which may induce an endothelium-dependent relaxation of the cavernous smooth muscles, would be good for erectile function. (Korean J Urol 2008;49: 366-372) 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏