At one time considered merely a monolayer of cells lining the vascular conduit, the endothelium has emerged recently as an organ with functions as complex as any in the body. A highly active regulatory organ, the endothelium senses and assesses the hemodynamic, humoral, and inflammatory signals to which it is constantly exposed by the blood and responds by secreting factors that affect vessel tone and structure. These interactions are not merely of academic interest. It has been increasingly recognized that endothelial dysfunction plays a pivotal role in the development and progression of atherosclerosis and coronary artery disease.
