[Oxidative stress in hypertension].

Reactive oxygen species (ROS) are involved in the pathogenesis of many cardiovascular diseases such as hypertension. In the circulation, ROS are generated by all vascular cells, i.e. endothelial cells, smooth muscle cells, and fibroblasts. Among the many enzymatic systems that are capable of producing ROS, NAD(P)H oxidase xantine oxidase and uncoupled endothelial nitric oxide synthase have been extensively studied in vascular cells. Enhanced ROS production (especially superoxide anion) causes diminished NO bioavailability and leads to endothelial dysfunction, which occurs for example in impaired vasorelaxation. Superoxide reacts with NO to form peroxynitrite, which can modify proteins and lipids to create nitrotyrosine, and nitrosothiols, isoprostanes, which are also able to modulate vascular tone. Several experimental observations have shown that a free radical scavenger may improve impaired endothelium-dependent vasodilatation and reduce elevated blood pressure in hypertension.