The antioxidant effects of green tea reduces blood pressure and sympathoexcitation in an experimental model of hypertension

Abstract

Background: Oxidative stress is a key mediator in the maintenance of sympathoexcitation and hypertension in human and experimental models. Green tea is widely known to be potent antioxidant.

Objective: We aimed to evaluate the effects of green tea in a model of hypertension.

Methods: Hypertension was induced by the nitric oxide synthase inhibitor [N-nitro-L-arginine-methyl-ester (L-NAME); 20 mg/kg per day, orally, for 2 weeks] in male Wistar rats. After the first week of L-NAME treatment, animals received green tea ad libitum for 1 week. At the end of the treatment period, blood pressure, heart rate, baroreflex sensitivity, renal sympathetic nerve activity, and vascular and systemic oxidative stress were assessed.

Results: L-NAME-treated animals exhibited an increase in blood pressure (165 ± 2 mmHg) compared with control rats (103 ± 1 mmHg) and green tea treatment reduced hypertension (119 ± 1 mmHg). Hypertensive animals showed a higher renal sympathetic nerve activity (161 ± 12 spikes/s) than the control group (97 ± 2 spikes/s), and green tea also decreased this parameter in the hypertensive treated group (125 ± 5 spikes/s). Arterial baroreceptor function and vascular and systemic oxidative stress were improved in hypertensive rats after green tea treatment.

Conclusions: Taken together, short-term green tea treatment improved cardiovascular function in a hypertension model characterized by sympathoexcitation, which may be because of its antioxidant properties.