Oxidative stress and coronary plaque stability.

Increased production of reactive oxygen species (ROS) in the vascular wall is a characteristic feature of disease states, including atherosclerosis, diabetes and hypertension. ROS, such as superoxide, reduce nitric oxide bioactivity by scavenging and cause oxidation of lipids and target proteins. In addition, recent work has revealed that ROS mediate a wide range of pathological processes in the endothelium, smooth muscle cells, and inflammatory cells.1 ROS are generated by enzyme systems present in cells in the vascular wall, including NAD(P)H oxidase, xanthine oxidase, and nitric oxide synthase. The activities and levels of these enzyme systems are increased in association with vascular disease risk factors2 and in vascular disease states in which oxidative stress is prominent, for example, in diabetes3 and atherosclerosis.