Angiotensin-converting enzyme in cardiovascular and adrenal tissues and implications for successful blood pressure management.

Components of the renin-angiotensin system, and the ability to synthesize these components locally, have been demonstrated in cardiovascular tissues. Locally generated angiotensin II may affect vascular tone, regional blood flow, cardiac contractility, and vascular and cardiac growth. Local renin-angiotensin systems may exert autocrine and paracrine functions, whereas the circulating system serves an endocrine function. Use of angiotensin-converting enzyme (ACE) inhibitors has provided further clarification of the activities of local renin-angiotensin systems. Tissue and systemic effects of these agents may prove equally important in determining their clinical efficacy. Experiments with quinapril demonstrated that inhibition of vascular ACE was a significant component of the antihypertensive effect of the drug. Differences at the tissue level may have implications for the efficacy and tolerability of a particular agent. Improved individualization of therapy may be accomplished by the use of newer ACE inhibitors with very favorable side effects profiles and tissue specificity. The newest agent, quinapril, appears to exert an important effect on vascular converting enzyme.