Measurement of intracavernosal catecholamine during a prostaglandin E₁ test

Background : Erectile dysfunction (ED) can be a cause of male infertility among young men. The prostaglandin E₁ (PGE₁) intracavernous injection test, an erectile function test, is known as an objective method of examining the penile vasculature system. However, some ED patients fail to sufficiently maintain an erection because of the stress load upon them during the test. Thus, we measured changes in catecholamine levels by stress loading when we performed dynamic infusion cavernosometry (DIC). : Among the 221 ED patients undergoing a PGE₁ test, 10 were selected as the subjects for the present study. These 10 patients were 25-56 years of age, with a mean of 32.8 years, whose maximal penile rigidity was normal, but in whom penile erection could not be maintained sufficiently in the PGE₁ test. Stress loading via vibratory sensory measurement during the PGE₁ test suppressed penile rigidity strongly. Catecholamine levels were measured by using blood samples obtained from the corpus cavernosum and the cubital vein when erection was suppressed by stress loading, pain caused by needle insertion, and also when erection recovered from the suppression. Dynamic infusion cavernosometry was performed after each blood sampling time, to check corporeal veno-occlusive function and cavernosal arterial flow. : Penile norepinephrine levels were 0.20 ± 0.06 ng/mL during a suppressed erection and 0.15 ± 0.03 ng/mL during an erection, showing a significantly higher level (Student's t-test, P = 0.0309) during suppressed erection. The results of the DIC measurement indicated a normal corporeal veno-occlusive function and cavernosal artery in all cases. : The results of the present study revealed that corporeal veno-occlusive function and cavernosal arterial flow are normal in men who have normal maximum penile rigidity, but cannot sufficiently maintain the erection in the PGE₁ test, suggesting the involvement of stress-induced penile norepinephrine in the suppression of erection maintenance. (Reprod Med Biol 2002; 1: 11-15).