Free radical generation, lipid peroxidation and essential fatty acids in uncontrolled essential hypertension

Vascular endothelium produces prostacyclin (PG12) and endothelium-derived vascular relaxing factor (EDRF), which are potent vasodilators and hence, may have a role in the regulation of blood pressure. Both PG12 and EDRF are readily degraded by free radicals, especially superoxide anion. Hence, we studied free radical generation and lipid peroxidation in patients with uncontrolled essential hypertension. It was observed that superoxide anion and hydrogen peroxide production by polymorphonuclear leukocytes (PMN) and the levels of lipid peroxides (measured by thiobarbituric acid assay) were higher in uncontrolled hypertensives compared to controls. Both free radical generation and the levels of lipid peroxides reverted to normal values when assayed after the control of hypertension. The calcium antagonist, verapamil, and beta-1 blocker, metoprolol, at the doses used inhibited free radical generation by phorbolmyristate acetate-stimulated PMNs. On the other hand, angiotensin II augmented free radical generation in normal PMN. In addition, it was also observed that both linoleic acid and arachidonic acid levels are low in the plasma of patients with hypertension compared to controls. These results suggest that increase in free radical generation by PMN and alterations in the plasma concentrations of essential fatty acids are closely associated with uncontrolled hypertension.