Concentrations of vasoactive intestinal polypeptide in corpus cavernosum and peripheral venous blood during prostaglandin E1-induced erection.

Vasoactive intestinal polypeptide (VIP) has been suggested to play a role as a nonadrenergic, noncholinergic neurotransmitter or neuromodulator involved in the process of erection. Until now, data about fluctuating concentrations of VIP in corpus cavernosum (CC) blood have been controversial. The present study describes a modified radioimmunoassay method that was developed in our laboratory for the determination of VIP in plasma. Examination of 12 patients suffering from impotentia coeundi (6 men with psychogenic impotence, 2 with induratio penis plastica, and 4 with impotence of vascular origin) showed that the concentrations of VIP in corpus cavernosum blood during pharmacologically induced erection did not increase in organically healthy men or in men with impotentia coeundi of vascular origin. The VIP concentrations in peripheral venous blood and those in CC blood were similar.