Abstract

This study was to test the inhibitory action of Mentha cordifolia (MC) extract on the development of hypertension in N^G-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. Male Sprague-Dawley rats received L-NAME (50 mg/kg/day) in drinking water and were either intragastrically administered with MC extract (200 mg/kg/day) or deionized water for 3 weeks. Significant increases in mean arterial blood pressure (MAP; 162.3 ± 2.7 vs 92.9 ± 5.4 mmHg), heart rate (HR; 414.7 ± 13.1 vs 331.7 ± 16.2 beat/min) and hindlimb vascular resistance (HVR; 39.1 ± 3.8 vs 12.6 ± 0.6 mmHg/min/100 g tissue/ml) in L-NAME-treated group compared to that of control group were observed. The MC extract markedly reduced the MAP about 16.7% in L-NAME group which was associated with reductions in HR and HVR. The MC extract alleviated a decrease in vascular responses to acetylcholine in the hypertensive rats. Increased levels of plasma malondialdehyde (MDA) and superoxide production in vascular tissues in hypertensive rats were restored by MC extract. The MC extract contains high level antioxidant in the form of total phenolic compounds. Our results indicated that the MC extract inhibited progress of hypertension in L-NAME group, and this effect might involve the antioxidant capacity of the extract.

Key words: Mentha cordifolia Opiz., L-NAME, hypertension, antioxidants, nitric oxide.