Angiotensin-converting enzyme in renal and cerebral tissue and implications for successful blood pressure management.

In addition to the classic circulating renin-angiotensin system, increasing evidence supports the existence of local tissue renin-angiotensin systems (vascular, cardiac, kidney, and brain) that appear to participate in cardiovascular homeostasis and in the pathogenesis of cardiovascular disorders via multiple autocrine and paracrine functions. Components of local systems have been detected in cardiovascular tissues. Studies with angiotensin-converting enzyme (ACE) inhibitors provide further evidence of the existence and importance of tissue renin-angiotensin systems. The blood pressure-lowering effect of quinapril, for example, correlated better with inhibition of tissue ACE (aorta) than with inhibition of plasma ACE. The effects of ACE inhibitors on local tissue renin-angiotensin systems (vascular in particular) may be the crucial determinant of response to treatment. Newer ACE inhibitors, such as quinapril, have favorable side effect profiles as well as apparent tissue specificity for the vascular renin-angiotensin system (and possibly other relevant cardiovascular tissue). Differentiation among ACE inhibitors should play an even more important role in the future for individualization of therapy.