The vasodilator effect of testosterone on the human internal spermatic vein and its relation to varicocele grade

Several animal and human studies in vivo and in vitro indicate that testosterone has vasodilatory effects on different vessels. However, the effect of testosterone on the internal spermatic vein is not clear. In addition, the role of testosterone in the pathophysiology of varicocele is not established. We investigated the effect of testosterone on the internal spermatic vein in vitro in patients with varicocele and analyzed its relation to varicocele grade.

Isolated internal spermatic veins were collected from patients who underwent varicocelectomy and orchiectomy. The preparations (3 to 4 mm rings) were mounted in an organ bath containing 10 ml Krebs-Henseleit solution on an L-shaped brace for tension measurement along the former circumferential axis. Changes in venous tension in the presence of testosterone (0.1 to 300 microM) were recorded isometrically by a force displacement transducer.

Cumulative concentrations of testosterone (0.1 to 300 microM) elicited concentration dependent relaxation of 45 mM KCl induced active tone in the internal spermatic vein (mean +/- SEM 60.97% +/- 5.05% of the KCl induced contraction). Relaxation to testosterone (1 to 300 microM) was significantly higher in 5 cases of grades 0 and 1 varicocele than in 15 of grades 2 and 3 varicocele (maximum relaxation response 78.58% +/- 8.25% vs 55.10% +/- 5.3% of the KCl induced contraction).

To our knowledge the current report is the first to describe testosterone induced relaxation of the human internal spermatic vein. The vasodilatory effect of testosterone on the human internal spermatic vein decreases in high grade varicoceles.