Spasmolytic Effect of Vitis Vinifera Leaf Hydroalcoholic Extract on Rat's Isolated Vas Deferens

Introduction: Many reports have shown that the grape (Vitis vinifera) seed extract induces antioxidant, hypotensive hypolipidemic, and vasodilatory effects. We have recently shown the relaxatory effect of grape leaf extract on rat's aorta, ileum, uterus and frog's heart rate and contractility. The objective of this study was to investigate the spasmolytic effect of Vitis Vinifera Leaf Hydroalcoholic extract (VLHE) on rat's isolated vas deferens.

Materials & Methods: Vas deferens of male adult rat (Sprague Dawley) was removed, placed in an organ bath containing Tyrode’s solution (30ºC, pH 7.4) and the bath bubbled with air. Then its contractions under 1 g initial tension, were recorded isometrically. The vas deferens was contracted either by KCl (80 mM) or adrenaline (2μg/ml).

 Results: The results demonstrated that the VLHE at 1, 2, 4 and 8 mg/ml reduced the vas deferens contractions evoked by KCl (80 mM) significantly (P<0.0001) and dose-dependently. VLHE (1, 2 and 4 mg/ml) also reduced the adrenaline-induced vas deferens contractions (P<0.0001). In calcium free Tyrod’s solution, KCl-induced contractions were occurred only after adding normal calcium (1.77 mM) to the organ bath solution. VLHE (3mg/ml) reduced the calcium-induced contraction by KCl too. The VLHE-induced vas deferens relaxation was unaffected by the β- adrenoceptor antagonist (propranolol, 3μM for 5 min). Nitric oxide synthase inhibitor (L-NAME, 300μM for 10 min) was unable to modify either KCl-induced contraction or the vas deferens relaxation induced by the extract.

Conclusion: These results suggested that the spasmolytic effect of Vitis vinifera leaf hydroalcoholic extract on rat's vas deferens occurred through the blockage of voltage dependent calcium channels (VDCC). Also, neither NO nor β-adrenoceptors were involved in this inhibitory effect of the extract.