Free Radicals in Cardiovascular Diseases

During the past several years, there has been a growing interest in the medical implications of free radicals. These chemical entities are common by-products of many oxidative biochemical reactions in the cell. Free radicals are essential to a number of normal biochemical and physiological processes. They are too reactive to be tolerated in living tissue, and aerobic organisms use sophisticated defense systems, enzymatic and nonenzymatic, for prevention of overload with free radicals and peroxides. 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. It is becoming well recognized that reactive oxygen species may be important mediators of cell injury in many cardiovascular diseases. This review concentrates on some of the considerable biochemical evidence concerning involvement of oxygen free radicals in several cardiovascular diseases: ischemia/reperfusion injury, atherosclerosis and hypertension. Since the current evidence shows that supplements and some of the cardiovascular drugs might possess useful antioxidant capacity, strategies for minimizing tissue injury caused by free radicals are briefly summarized.