In vitro vasodilatory effect of aqueous leaf extract of Thymus serrulatus on thoracic aorta of Guinea pigs

Objective:To investigate the vasodilatory effecl of Thymus serrulatus(T.serrulatus) aqueous leaf extract on KCl(high K^+.80 mmol/L) induced precontracted isolated thoracic aorta rings on guinea pigs and the role of aorta endothelium on this action.Methods:Guinea pig thoracic aorta was removed and placed in an organ bath containing Krebs-Henseleit solution and aorta contractions were recorded isometrically.Results:The results revealed that T.serrulalus aqueous leaf extract(0.5-5 mg/mL)significantly(P<0.001) reduced KCl-induced contractions of guinea pig thoracic aorta in both intact(n=5) and denuded(n=5) endothelium in a concentration dependent manner,and the vasodilatory effect of the extract on intact endothelium was significantly(P<0.05) higher than that on denuded endothelium.Glibenclamide(10 μmol/L) significantly(P<0.001) increased the vasodilatory effect of extract in intact endothelium as compared to methylene blue(10μmol/L).atropine(10 μmol/L) and indomethacin(10 μmol/L).The effecl was more obvious on intact than that on denuded endothelium.Conclusions:The present findings demonstrate that T.serrulalus aqueous leaf extract has vasodilator)' activity which might result in antihypertensive effect and its vasodilatory effect is endothelium-dependent.This might support the traditional claim of the plant in hypertensive.