Contractility of diabetic human corpus cavernosum smooth muscle in response to serotonin mediated via Rho-kinase.

Background/aims: Serotonin (5-hydroxytryptamine, 5-HT)-induced contraction and the involvement of RhoA/Rho-kinase pathway in the 5-HT-induced contraction was investigated isometrically in vitro in both diabetic and nondiabetic human corpus cavernosum (HCC) tissues.

Methods: HCC tissues were obtained from 12 patients. The response to 5-HT (10(-9) to 10(-5) mol/l) was studied in isolated HCC tissues in the absence and in the presence of a Rho-kinase inhibitor (Y-27632).

Results: Preincubation with Y-27632 attenuated maximum contractions induced by 5-HT in tissues of both nondiabetics and diabetics. When diabetic and nondiabetic groups were compared, no significant difference was seen in 5-HT-induced contraction alone, but in the presence of Y-27632, 5-HT-induced contraction was significantly higher in the diabetic group.

Conclusion: These results suggest that the Rho-kinase-mediated pathway plays an important role for 5-HT-induced contraction in diabetic corpus cavernosum tissues.