Contractility changes of the deep dorsal penile vein due to serotonin

Penile erection is a complex neurovascular phenomenon that takes place with the active contribution of arterial and sinusoidal structures. However, some authors claim that larger veins including the deep dorsal veins that produce contractions, might be involved in the physiology of erection. This study was designed to clarify the contractile properties of deep dorsal penile veins (DDPV).

The effect of serotonin (5-HT), noradrenaline (NA), adenosine triphosphate (ATP) and acethylcholine (Ach) on the isolated DDPVs of 16 impotent men, 9 with veno-occlusive dysfunction and 7 without venous leakage, and 5 potent men (controls) who underwent radical prostatectomy, were examined in vitro.

Although NA, ATP and Ach had no effect, 5-HT produced concentration-dependent contractions. Emax and pEC50 of 5-HT were 411 +/- 10 mg., 5.92 +/- 0.25; 1020 +/- 260 mg., 5.83 +/- 0.24 and 160 +/- 40 mg., 6.4 +/- 0.22 in controls and patients who had venous leakage and no venous leakage, respectively. Samples of controls were contracted only with 5-HT2 agonist, DOI (pEC50 = 5.63 +/- 0.02), and these contractions were antagonized with 5-HT2 antagonist ketanserin. On the other hand, both DOI (pEC50 = 6.30 +/- 0.77) and 5-HT1 agonist, 5-CT (pEC50 = 6.23 +/- 0.21) produced venoconstriction in patients with veno-occlusive dysfunction.

The present findings suggest that 5-HT receptor functions in the DDPVs are of 5-HT2 subtype in potent men and the altered response to 5-HT in patients with veno-occlusive disease may play a role in the pathophysiology of impotence.