Testosterone Might Cause Relaxation of Human Corpus Cavernosum by Potassium Channel Opening Action

OBJECTIVES To investigate the effect of testosterone on contractile tone of endothelium-denuded human corpus cavernosum strips. Human studies designed to examine a possible relaxant effect of testosterone on corpus cavernosal circulation are lacking. METHODS Testosterone (0.1-300 mu M) was added cumulatively to organ baths after precontraction of isolated human corpus cavernosum strips (n = 5) with KCl (45 mM). Testosterone-induced response; were tested in the presence of nonselective, large, conductance Ca2+-activated and voltage-sensitive K+ channel inhibitor tetraethylammonium (1 mM), adenosine triphosphate-sensitive K+ channel inhibitor glibenclamide (10 mu M), voltage-dependent inward rectifier K+ channel inhibitor barium chloride (30 mu M) and voltage-sensitive K+ channel inhibitor 4-aminopyridine (1 mM). RESULTS Testosterone (0.1-300 mu M) produced relaxation in human corpus cavernosum (maximum relaxation 65.4% +/- 3.3% of KCl-induced contraction) that reached a maximum at a concentration of 300 mu M. Testosterone-induced relaxation was significantly attenuated by glibenclamide, but it was not affected by the other K+ channel inhibitors (tetraethylammonium, barium chloride, or 4-aminopyridine). CONCLUSIONS Testosterone might induce relaxation in human isolated corpora cavernosa strips by activation of smooth muscle adenosine triphosphate-sensitive K+ channels. This finding Suggests that testosterone, in addition to its known endothelial action, might regulate erectile function locally by its action on the smooth muscle of the human corpus cavernosum. UROLOGY 74: 229-232, 2009. (c) 2009 Elsevier Inc. All rights reserved.