The vascular endothelium modulates vascular tone and the expression of a number of vascular genes mainly by producing vasoactive autacoids such as nitric oxide (NO) and the superoxide anion (O2 -). Hypertension, arteriosclerosis, and ischemic heart disease are all associated with dysregulation of endothelial cell function. This is related to an imbalance in the production of endothelial NO and vascular O2 -, which results in the shutdown or inactivation of intrinsic antiatherogenic processes. Clinical and experimental evidence indicates that angiotensin-converting enzyme (ACE: kininase II) inhibitors are able to halt the development of endothelial dysfunction, and, in certain situations, to restore the balance in vascular autacoid production...