REVIEW There are two isoforms of ACE: the somatic isoform, which exists as a glycoprotein comprised of a single polypeptide chain of 1277; and the testicular isoform, which has a lower molecular mass and is thought to play a role in sperm maturation and binding of sperm to the oviduct epithelium. Somatic ACE has two functionally active domains, N and C, which arise from tandem gene duplication. Although the two domains have high sequence similarity, they play distinct physiological roles. The C-domain is predominantly involved in blood pressure regulation while the N-domain plays a role in hematopoietic stem cell differentiation and proliferation. ACE inhibitors bind to and inhibit the activity of both domains, but have much greater affinity for and inhibitory activity against the C-domain. Quinaprilat, the principle active metabolite of quinapril, competes with ATI for binding to ACE and inhibits and enzymatic proteolysis of ATI to ATII. Decreasing ATII levels in the body decreases blood pressure by inhibiting the pressor effects of ATII as described in the Pharmacology section above. Quinaprilat also causes an increase in plasma renin activity likely due to a loss of feedback inhibition mediated by ATII on the release of renin and/or stimulation of reflex mechanisms via baroreceptors.
Khan BV, Sola S, Lauten WB, Natarajan R, Hooper WC, Menon RG, Lerakis S, Helmy T: Quinapril, an ACE inhibitor, reduces markers of oxidative stress in the metabolic syndrome. Diabetes Care. 2004 Jul;27(7):1712-5.
Kieback AG, Felix SB, Reffelmann T: Quinaprilat: a review of its pharmacokinetics, pharmacodynamics, toxicological data and clinical application. Expert Opin Drug Metab Toxicol. 2009 Oct;5(10):1337-47.
Pitt B, O'Neill B, Feldman R, Ferrari R, Schwartz L, Mudra H, Bass T, Pepine C, Texter M, Haber H, Uprichard A, Cashin-Hemphill L, Lees RS: The QUinapril Ischemic Event Trial (QUIET): evaluation of chronic ACE inhibitor therapy in patients with ischemic heart disease and preserved left ventricular function. Am J Cardiol. 2001 May 1;87(9):1058-63.
Tsikouris JP, Suarez JA, Meyerrose GE, Ziska M, Fike D, Smith J: Questioning a class effect: does ACE inhibitor tissue penetration influence the degree of fibrinolytic balance alteration following an acute myocardial infarction? J Clin Pharmacol. 2004 Feb;44(2):150-7.
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