Spasmolytic effect of Vitis vinifera leaf extract on rat colon

ABSTRACT

Vitis vinifera [grape] leaf has been used traditionally to treat diarrhea and its extract induces relaxation in rat aorta and uterus. The aim of present study was to investigate the effect of grape leaf hydroalcoholic extract [GLHE] on rat colon contractions induced by some spasmogens. A piece of distal colon from male adult Wistar rats were dissected and mounted in an organ bath containing Tyrode solution and colon contractions recorded by an isotonic transducer under 1g resting tension. The GLHE [0.5- 4 mg/ml] reduced the contractions induced by KCl [60 mM], BaCl2 [4 mM], acetylcholine [1 micro M] dose-dependently [P<0.001]. The spasmolytic effect of GLHE on ACh-induced contraction was unaffected by propranolol [1 micro M], phentolamine [1 micro M], L-NAME [300 micro M], and naloxone [1micro M]. In Ca2+-free but rich in KCl [120 mM] Tyrode solution, cumulative concentrations of CaCl2 induced colon contractions which, were inhibited by the extract. Glibenclamide [3 micro M] had no effect on the extract spasmolytic activity, but tetraethylammonium [5 mM] contracted the pre-relaxed colon induced by the extract. Results suggest that the grape leaf hydroalcoholic extract spasmolytic effect is due to the blockade of the voltage dependent calcium channels and activation of Ca2+-operated potassium channels