Purpose: Men become impotent when exposed to hyperprolactinemia. To clarify its mechanisms the effects of intracorporal infusion of prolactin on electrically induced penile erection were evaluated in 12 male dogs.
Materials and methods: Prolactin (10 micrograms./ml.) or control saline was directly infused into the corpus cavernosum penis 5 minutes before electrical pulse stimulation of the pelvic nerve and the intracorporal pressure was monitored.
Results: In 8 dogs erection was markedly suppressed or completely abolished by prolactin. In the remaining 4, this effect of prolactin became manifest only when the ipsilateral internal pudenal artery was ligated. Saline infusion was without effect.
Conclusions: An excess of prolactin directly inhibited the smooth muscle relaxation of corpus cavernosum penis.