ABSTRACT
Up until the late 1970s, the vascular endothelium was considered as a passive lining of flat cells that separated the load-bearing elements of the vascular media from the flowing blood. Over the subsequent 30 or more years, it has become apparent that the endothelium produces a host of chemical substances, notably nitric oxide (NO), endothelin, prostacyclin, and angiotensinogen, which are designed to maintain homeostasis through effects on elements of blood in the lumen, on the intimal surface which is exposed to blood, within the intima itself, and on vascular smooth muscle cells in the media (Vane et al., 1990; Celermajer, 1997).
