RESUMO
Over the last two decades, it has become increasingly clear that reactive oxygen species (ROS), including free radicals are involved in cardiovascular disease. In recent years, there has been a growing interest in the clinical implications of these oxidants. The ROS are common by-products of many oxidative biochemical and physiological processes. They can be released by xanthine oxidase, NAD(P)H oxidase, lipoxygenases, mitochondria, or the uncoupling of nitric oxide synthase in vascular cells. ROS mediate various signaling pathways that underlie vascular inflammation in atherogenesis. Various animal models of oxidative stress support that ROS have causal role in atherosclerosis and other cardiovascular diseases. They are too reactive to be tolerated in living tissue, and aerobic organisms use sophisticated defense system, both enzymatic and non-enzymatic for prevention of overload of free radicals. In a number of pathophysiological conditions, the delicate equilibrium between free-radical production and antioxidant capability can be altered in favor of the former, thus leading to oxidative stress and increased tissue injury. This review focuses on the biochemical evidences concerning involvement of ROS in several cardiovascular diseases, namely atherosclerosis, heart failure, hypertension and ischemia/reperfusion injury.