Misoprostol induces relaxation of human corpus cavernosum smooth muscle: comparison to prostaglandin E1

Prostaglandin E1 (PGE1) relaxes trabecular smooth muscle by interacting wit h specific G-protein coupled receptors on human corpus cavernosum smooth mu scle and increasing intracellular synthesis of cAMP, Misoprostol (Cytotec(T M)), is an oral prostaglandin E analogue. The purpose of this study was to compare the functional activity of misoprostol with PGE1 in human corpus ca vernosum and cultured human corpus cavernosum smooth muscle cells. Misopros tol, misoprostol free acid or PGE1 induced dose-dependent relaxations in st rips of human corpus cavernosum. At concentrations greater than 10(-6) M, t issue recontraction was observed with all three agents. This was abrogated by pretreatment with the thromboxane A2 receptor antagonist SQ29,548. From these observations, we conclude that misoprostol is activated by human corp us cavernosum in situ and relaxes phenylephrine-precontrated tissue strips in vitro. This relaxation response is mediated by the increased cAMP synthe sis by these agents.