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

Abstract

Objective: To 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. 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. 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. Conclusions: The 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.

Keywords

• Thymus serrulatus
• Guinea pig
• Aqueous extract
• Endothelium
• Organ bath
• Vasodilatory effect