Comparison between plasma concentrations of testosterone, nitric oxide and endothelin 1-2 in penile and brachial venous blood: preliminary results in men with psychogenic impotence.

In the present study venous plasma concentrations of testosterone (T), nitric oxide (NO) and endothelin 1-2 (ET1-2) in the flaccid penis and brachial blood were measured in men with psychogenic impotence. T and NO were significantly lower in the penile venous blood, while ET1-2 showed no statistical difference. These data support the hypothesis of testosterone dependence of penile nitric oxide synthesis (NOS).