Relaxatory effect of Vitis vinifera leaf extract on rat isolated trachea

In previous studies, we have shown the relaxatory effect of grape leaf (Vitis vinifera) extract on isolated ileum, uterus and aorta. In rat aorta it was revealed that the NO and endothelium are involved in the relaxation induced by grape leaf extract. The aim of present study was to investigate the effect of the Vitis vinifera leaf hydroalcoholic extract (VLHE) on rat trachea precontracted by Ach and KCl. Extract was prepared by maceration method using 70% alcohol for 72 hours and then, the solvent was evaporated. Male Sprague Dawley rats were anaesthetized by ketamine hydrochloride (50 mg/kg i.p.), the trachea (5-6 cartilage rings) were isolated and suspended in an organ bath containing Kreb’s solution (37?C, pH 7.4) bubbled with oxygen. Following 60 min period equilibrium, tissue was contracted by either Ach (55 µM) or KCl (60 mM) under 1.5 g initial tension and tissue responses were recorded isometrically. After reaching to plateau, different concentrations of VLHE (0.5, 1, 2, 4 and 8 mg/ml) applied to the organ bath in a non-cumulative manner. Results are presented in mean±SEM of g contraction force. Trachea precontracted by Ach or KCl were relaxed by VLHE significantly (P