Inhibition by sildenafil of contractility of isolated non-pregnant human myometrium

Abstract

Objective: To investigate the ability of sildenafil to inhibit the contractility of isolated non pregnant human myometrium. Materials and Methods: The inhibitory effect of three concentrations (3, 10, and 30 μM) of sildenafil on 55 mM KCl-induced contractility of isolated non-pregnant human myometrium was studied. The ability of the guanylyl cyclase inhibitor ODQ (10 μM), the adenylyl cyclase inhibitor MDL-12,330A (10 μM), the non-specific potassium channel blocker TEA (2 mM), and the calcium-sensitive potassium (BKCa) channel blocker iberiotoxin (100 nM) to reverse the inhibition of 10 μM sildenafil on KCl-induced myometrial contractility was also studied. Results: Sildenafil produced a concentration-dependent inhibition of KCl-induced myometrial contractility that was statistically significant at all three concentrations of sildenafil used. The inhibition by 10 μM sildenafil of KCl-induced myometrial contractility was not reversed by the concurrent administration of ODQ or MDL-12,330A. The inhibition of 10 μM sildenafil of myometrial contractility was partially reversed by concurrent administration of TEA and totally and significantly reversed by the concurrent administration of iberiotoxin. Conclusions: These results suggest that sildenafil inhibits the contractility of isolated non-pregnant human myometrium. The results suggest that sildenafil does so by opening BKCa channels.