Oxidative stress in patients with essential hypertension.

ABSTRACT

BACKGROUND: Free oxygen radicals react with membrane lipids to form lipid hydroperoxides, a destructive process known as lipid peroxidation. Lipid hydroperoxides decompose to form a variety of products including malondialdehyde, which is used as an indicator of the oxidative damage of cells and tissues. Endogenous antioxidant enzymes such as superoxide dismutase counteract the oxidative damage from oxidative stress. There is increasing evidence that free radicals are involved in the pathogenesis of hypertension by altering endothelial function. We evaluated the oxidative stress and endogenous enzymatic antioxidant status in patients with essential hypertension before and 3 months after treatment with antihypertensives. METHODS: Fifty patients with essential hypertension attending the outpatient services of the Department of Medicine, Institute of Medical Sciences, Banaras Hindu University and 20 age- and sex-matched healthy controls were studied. The serum malondialdehyde and superoxide dismutase levels were measured in patients at the time of presentation and after 3 months of antihypertensive treatment. No antioxidants were given to the patients during the period of the study. RESULTS: The mean (SD) serum malondialdehyde level was found to be significantly higher (0.33 [0.07] mmol/L) in patients with hypertension compared with controls (0.21 [0.05] mmol/L; p < 0.001). This showed a significant decrease following antihypertensive therapy (0.23 [0.06] mmol/L; p < 0.001) compared with pre-treatment values. The serum superoxide dismutase activity was significantly lower in patients (6.93 [1.35] mg protein/ml of serum) compared with controls (20.12 [3.65] mg protein/ml serum; p < 0.001) at the time of presentation and, compared with the pre-treatment values, increased significantly after 3 months of treatment (10.66 [2.91] mg protein/ml of serum; p < 0.001). CONCLUSION: Our study shows that essential hypertension is associated with increased oxidative stress and reduced antioxidant status. Adequate control of blood pressure with antihypertensive therapy decreases oxidative stress and improves the antioxidant status in these patients.