The role of the renin-angiotensin system in vascular health: use of ACE inhibition to improve vascular function.

Hypertension is a syndrome in which dysfunction of the blood vessels and of neuroendocrine systems play a major role. Arteriosclerosis and atherosclerosis are distinct processes in arterial disease. Arteriosclerosis begins with thickening and hardening of the arterial wall, with loss of elasticity. Atherosclerosis is an inflammatory process that begins with endothelial dysfunction, and leads to vascular occlusion. The endothelial dysfunction that causes atherosclerosis and coronary artery disease results from an imbalance between nitric oxide and angiotensin-II. This balance becomes tipped toward angiotensin-II in the presence of hypertension. When arteries stiffen as a result of hypertension and aging, they are not able to store blood volume properly, systolic blood pressure rises, and pulse pressure widens. Because the tissue renin-angiotensin system is responsible for promoting the adverse structural arterial changes, inhibition of angiotensin-converting enzyme (ACE) is effective in restoring the health of both large and small arteries by blocking angiotensin and by increasing bradykinin.