Pipersarmentosumattenuatesdexamethasone-induced hypertensionbystimulatingendothelialnitricoxide synthase

Abstract

Reduced endothelial nitric oxide (NO) synthesized by endothelial nitric oxide synthase (eNOS) in the vasculature is a feature of endothelial dysfunction. Dexamethasone causes secondary hypertensionby inhibiting eNOS activity. Piper sarmentosumis an herb with anti-hypertensive effect. The aim of this study was to evaluate the anti-hypertensive effect of aqueous extract of P. sarmentosum(AEPS) in dexamethasone (Dex)-induced hypertensive rats.A total of 30 male Sprague Dawley rats were divided into five groups including control, AEPS (500 mg/kg/day, orally), Dex (20 μg/kg/day, subcutaneously), Dex (20 μg/kg/day) + AEPS (500 mg/kg/day) and Dex (20 μg/kg/day) + captopril (40mg/kg/day, orally). Blood pressure was measured using tail-cuff method at baseline and fortnightlythereafter. The rats were sacrificed and the serum was collected to quantify the amount of NO after28 days of treatment. Aortic samples were homogenized for measurement of eNOS mRNA expression, protein level and activity. Treatment of Dex-induced hypertensive rats with AEPS lowered systolic blood pressure (P< 0.001) and diastolic blood pressure (P< 0.01), increased eNOS mRNA expression (P< 0.01), eNOS protein (P< 0.01), eNOS activity (P< 0.05) and NO level (P< 0.05). In conclusion, AEPS reducesthe blood pressure of Dex-induced hypertensive rats as it shows positive effects on eNOS and NO production.