Y-27632, an inhibitor of Rho-kinase, antagonizes noradrenergic contractions in the rabbit and human penile corpus cavernosum.

We have examined the effect of an inhibitor of Rho-kinase, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride monohydrate (Y-27632), on the contractions elicited by noradrenergic nerve stimulation and by phenylephrine in the human and rabbit penile corpus cavernosum. In both tissues, after treatment with scopolamine (10 microM) and N(G)-nitro-L-arginine methyl ester (L-NAME; 300 microM), electrical field stimulation (EFS) elicited noradrenergic contractions. These contractions were inhibited by Y-27632 in a concentration-dependent manner. The compound caused concentration-dependent relaxation of phenylephrine-contracted tissues, which were treated with scopolamine (10 microM), guanethidine (10 microM) and L-NAME (300 microM). These results suggest that Rho-kinase is involved in noradrenergic contractile pathway in the cavernosal smooth muscle of the penis.