INTRAURETHRALLY INFUSED CAPSAICIN INDUCES PENILE ERECTION IN HUMANS

Capsaicin-sensitive primary afferents widely innervate the genitourina ry tract and play an important role in the integration of various mech anisms which activate reflexes leading to penile erection. We investig ated the effect of intraurethral capsaicin infusion in psychogenically impotent men. The 20 patients were prospectively randomized to four g roups, each of five men. Group A received intraurethral infusion of sa line solution, group B intraurethral capsaicin (10(-5) M), group C int racavernosal papaverine hydrochloride (8 mg) plus intraurethral saline infusion, and group D intracavernosal papaverine hydrochloride (8 mg) plus intraurethral capsaicin (10(-5) M). The penile response was reco rded real-time. Intraurethral capsaicin induced penile erection, as di d the papaverine injection, while saline infusion was without effect. The erectile response to intraurethral infusion of capsaicin is sugges ted to involve activation of a urethra-corpora cavernosa reflex are. F urther studies are necessary to clarify if this are is integrated at c entral nervous system level or is locally triggered, and if it may hav e pathophysiologic implications.