The effect of Korean red ginseng extract on the relaxation response in isolated rabbit vaginal tissue and its mechanism

Introduction. Ginseng is an herbal medicine with a variety of biological activities. Aim. The purpose of this study was to investigate the effect of Korean red ginseng (KRG) extract on the relaxation response in isolated rabbit vaginal tissue and its mechanism as a potential therapeutic agent for female sexual dysfunction. Method. Strips of rabbit vagina were mounted in organ chambers to measure isometric tension. After the strips were precontracted with phenylephrine, the contractile responses to KRG extract (1-20 mg/mL), nitric oxide inhibitor (N[omega]-nitro-L-arginine methyl ester [L-NAME]), an inhibitor of soluble guanylate cyclase (methylene blue), an inhibitor of Ca2+-activated K+ channels (tetraethylammonium [TEA]), and an adenosine triphosphate (ATP)-sensitive K+ channel blocker (glybenclamide) were examined. Main Outcome Measures. The relaxation of the vaginal tissue strip was assessed after treating KRG extract or other chemicals. Results. KRG (1-20 mg/mL) extract relaxed the vaginal tissue strip in a dose-dependent manner up to 85%. The relaxation effect was significantly inhibited by L-NAME (30 mu M) and methylene blue (30 mu M) (P < 0.05). In addition, KRG inhibited the contraction induced by depolarization with 10, 20, and 40 mM KCl. The KRG-induced relaxation effect was significantly inhibited by TEA (300 mu M) (P < 0.05), and not by glybenclamide (30 mu M). Conclusions. These data show that KRG extract has a relaxing effect on rabbit vaginal smooth muscle tissue. These effects might be mediated partly through the NO pathway and hyperpolarization via Ca2+-activated K+ channels.