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

ABSTRACTObjectiveTo investigate the vasodilatory effect 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.MethodsGuinea pig thoracic aorta was removed and placed in an organ bath containing Krebs-Henseleit solution and aorta contractions were recorded isometrically.ResultsThe results revealed that T. serrulatus 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 (10 µmol/L), atropine (10 µmol/L) and indomethacin (10 µmol/L). The effect was more obvious on intact than that on denuded endothelium.ConclusionsThe present findings demonstrate that T. serrulatus aqueous leaf extract has vasodilatory 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.