The relaxatory effect of VITIS VINIFERA leaf extract on rat uterus has been reported and it was postulated that, the extract relaxed through the blockade of voltage dependent calcium channels. The extract also, relaxed rat aorta through NO and was dependent on the functional endothelium. In the present study, the effect of VITIS VINIFERA hydroalcoholic leaf extract (VHLE) on rat vas deferens precontracted by KCl and epinephrine was investigated.
Extract was prepared by maceration method using 70% alcohol and then the solvent was evaporated. The isolated vas deferen of adult Sprague-Dawley rat was suspended in an organ bath containing Tyrod’s solution (30?C, pH 7.4) bubbled with air. Following 30 min period equilibrium, tissue was contracted by either epinephrine (EN, 2 µg/ml) or KCl (80 mM) under 1 g initial tension and tissue responses was recorded isometrically. VLHE was applied to the organ bath in a non-cumulative manner. Results are presented in mean±SEM of (g) contraction force or percentage of relaxation (%).
VHLE (1, 2, 4 and 8 mg/ml) reduced KCl-induced contractions significantly (P<0.0001) and dose dependently. Applying extract (1, 2, 4 mg/ml) prior adding EN, also reduced the vas deferens EN-induced contractions significantly (P<0.0001) and dose dependently. In Ca2+-free Tyrod’s solution, KCl-induced contraction occurred only after adding Ca2+ (1.77 mM). However, in the presence of extract (3 mg/ml), the vas deferens contractility reduced significantly (P<0.05). Applying neither NO synthase inhibitor (L-NAME, 300 µM, 15 min) nor ?-adrenergic receptor antagonist (propranolol, 1 µM) to the organ bath prior evoked contractions by KCl did not modify the vas deferens relaxation induced by extract (3 mg/ml).
It seems that the VITIS VINIFERA leaf hydroalcoholic extract (VLHE) reduced vas deferens contractions through blockade of voltage dependent calcium channels. On the other hand, neither nitric oxide (NO) nor ?-adrenergic receptors are involved in this relaxatory effect of VLHE.