Bronchodilatory Activity of Vitis vinifera Leaf Hydroalcoholic Extract in Rat

Several reports have shown the various effects of grape (Vitis vinifera) seed extract such as antioxidant, hypotensive, hypolipidemic and vasodilatory effects. The aim of present study was to investigate the effect of grape leaf hydroalcoholic extract on isolated rat tracheal contractions induced by KCl and acetylcholine. The trachea was removed from male adult Sprague-Dawley rat and placed in an organ bath containing Krebs-Henseleit solution and contractions were recorded isometrically. The results demonstrate that the grape leaf extract at 0.5, 1, 2, 4 and 8 mg/ml significantly reduces the tracheal contractions induced by KCl (60 mM) dose-dependently (P<0.0001). Acetylcholine (55 µM)induced tracheal contractions were also attenuated at the same concentration of the extract (P<0.0001). The grape leaf extract induced relaxation in the KCl-induced contraction in trachea was unaffected neither by nitric oxide (NO) synthase inhibitor (L-NAME, 100 µM) nor by betaadrenoceptor antagonist (propranolol 1 µM). Our results suggest that the bronchodilatory effect of grape leaf extract is mediated via the voltage dependent calcium channels. Furthermore, the betaadrenergic and NO are not involved.