Decreased endogenous antioxidant enzymatic status in essential hypertension

Several lines of evidence suggest that patients with essential hypertension have impaired endothelial nitric oxide activity and increased superoxide a nion production. However, the mechanisms underlying these abnormalities rem ain unknown, We measured enzymatic superoxide dismutase (SOD) and glutathio ne peroxidase (GPX) activities in erythrocytes and whole blood, respectivel y, in 30 newly-diagnosed, normolipidaemic untreated mild hypertensive patie nts and in 164 age-matched healthy controls. SOD and GPX activities in hype rtensive patients (806 +/- 225 U/Hb.g and 5491 +/- 2073 U/L, respectively) were significantly lower than in the control group (931 +/- 202 U/Hb.g and 6669 +/- 1560 U/L, respectively) (P < 0.005), No significant association wa s found between these antioxidant enzyme activities and blood pressure in n ormotensive controls, In the hypertensives, only log-transformed SOD activi ty showed a significant negative correlation with systolic and diastolic bl ood pressure (r = 0.37, P < 0.05; r = 0,64, P < 0.0001, respectively). The low endogenous antioxidant enzyme activities observed may in turn result in decreased superoxide anion removal leading to nitric oxide inactivation.