Role of different types of potassium channels in the relaxation of corpus cavernosum induced by resveratrol

BACKGROUND: Resveratrol (RVT), one of the most commonly employed dietary polyphenol, is used in traditional Japanese and Chinese medicine for treatment of cardiovascular diseases. Recently, we have shown that RVT has a potent relaxant effect on rat corpus cavernosum via endothelium-dependent and -independent mechanisms. OBJECTIVE: The present study addressed the question whether different types of potassium channels are involved in the endothelium-dependent and -independent mechanism of corpus cavernosum relaxation induced by RVT. MATERIALS AND METHODS: Strips of corpus cavernosum from rats were mounted in an organ-bath system for isometric tension studies. RESULTS: RVT (1-100 μmol/L) produced concentration-dependent relaxation responses in rat corpus cavernosum pre-contracted by phenylephrine. The non-selective potassium channels blocker tetraethylammonium chloride (TEA, 10 mmol/L), ATP-sensitive potassium (K(ATP)) channels blocker glibenclamide (10 μmol/L), and inward rectifier potassium (Kir) channels inhibitor barium chloride (BaCl(2), 30 μmol/L) caused a significant inhibition on the relaxation response to RVT, whereas voltage-dependent potassium channels inhibitor 4-aminopyridine (4-AP, 1 mmol/L), and large conductance calcium-activated potassium (BK(Ca)) channels inhibitor iberiotoxin (IbTX, 0.1 μmol/L) did not significantly alter relaxant responses of corpus cavernosum strips to RVT. In addition, relaxant responses to RVT did not significantly inhibited by the combination of selective inhibitors of small and intermediate conductance BK(Ca) channels (0.1 μmol/L charybdotoxin and 1 μmol/L apamin, respectively). CONCLUSION: These results demonstrated that endothelial small and intermediate conductance BK(Ca) channels are not thought to be an important role in RVT-induced endothelium-dependent relaxation of corpus cavernosum. The endothelium-independent corpus cavernosum relaxation induced by RVT is seems to largely depend on Kir channels and K(ATP) channels in corporal tissue.