Testosterone relaxes human internal spermatic vein through potassium channel opening action.

OBJECTIVE

To investigate the relation of testosterone-induced relaxation with smooth muscle K+ channels in human internal spermatic veins. Testosterone induces relaxation in human isolated internal spermatic veins, and this effect decreases in high-grade varicocele (recently reported).

METHODS

The responses of isolated internal spermatic veins from patients with varicocele were recorded isometrically using a force displacement transducer. After contracting the venous rings with 45 mM KCl, relaxation with testosterone (0.1-300 μM) was recorded in the absence or presence of large conductance calcium-activated K+ channel and the voltage-sensitive K+ channel inhibitor tetraethylammonium, adenosine triphosphate-sensitive K+ channel inhibitor glibenclamide, voltage-dependent inward rectifier K+ channel inhibitor barium chloride, and voltage-sensitive K+ channel inhibitor 4-aminopyridine.

RESULTS

Testosterone induced relaxation in human isolated internal spermatic veins in the absence of inhibitors (maximal effect 52.88±6.72, n=24). Although tetraethylammonium, barium chloride, and 4-aminopyridine did not alter the testosterone-induced relaxant responses, GLI inhibited these responses.

CONCLUSIONS

These results have demonstrated that testosterone induces relaxation in human isolated internal spermatic veins of patients with varicocele by way of adenosine triphosphate-sensitive K+ channels.