fr-173657 and Heart-Failure

In congestive heart failure, angiotensin-converting enzyme inhibitors (ACEIs) may prevent cardiac fibrosis via interaction with both angiotensin II and endothelin-1, which enhance myocardial collagen synthesis. However, whether endogenous bradykinin with an ACEI modifies the cardiac collagen architecture, affecting the endothelin system, has not yet been fully elucidated. We evaluated the changes in circulating hormonal factors, myocardial fibrosis and cardiac gene expression closely linked with heart failure, using an orally active specific bradykinin type 2 receptor antagonist, FR173657 (0.3 mg/kg/day, n = 6), with an ACEI, enalapril (1 mg/kg/day), in dogs with tachycardia-induced congestive heart failure (270 p.p.m., 22 days) and compared the effects with enalapril alone (n = 6). Although there were no differences observed in blood pressure, plasma renin activity, aldosterone and endothelin-1 levels, combined FR173657 significantly increased the cardiac expression of preproendothelin- 1 mRNA (P < 0.05) and collagen type I and type III mRNA (P < 0.05), and cardiac collagen deposits (P < 0.05), and decreased eNOS gene expression (P < 0.05) in the left ventricle compared with the ACEI-treated group. Furthermore, there was a significant negative correlation between the expression of preproendothelin- 1 and eNOS mRNA levels (r = -0.708, P < 0.001). In conclusion, bradykinin may prevent cardiac fibrosis in part via suppression of the local endothelin system in the failing heart through the enhancement of nitric oxide production under chronic angiotensin-converting enzyme inhibition.

Topics: Aldosterone; Angiotensin-Converting Enzyme Inhibitors; Animals; Bradykinin; Bradykinin B2 Receptor Antagonists; Collagen; Disease Models, Animal; Dogs; Enalapril; Endothelin-1; Fibrosis; Heart Failure; Hemodynamics; Myocardium; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Quinolines; Receptor, Bradykinin B2; Renin; RNA, Messenger

Both systolic and diastolic cardiac dysfunction coexist in various degrees in the majority of patients with heart failure. Although ACE inhibitors are useful in the treatment of heart failure, the roles of bradykinin in the systolic and diastolic properties of left ventricular function under long-term treatment of ACE inhibitor have not been fully elucidated. We therefore evaluated the changes in left ventricular function, histomorphometry, and the expression of several failing heart related genes, by use of an orally active specific bradykinin type 2 receptor antagonist, FR173657 (0.3 mg/kg per day), with an ACE inhibitor, enalapril (1 mg/kg per day), in dogs with tachycardia-induced heart failure (270 ppm, 22 days) and compared the effects to enalapril alone. Although there were no differences observed in blood pressure, left ventricular dimension, and percentage of fractional shortening, FR173657 significantly increased left ventricular filling pressure (P<0.01), prolonged the time constant of relaxation (P<0.05), and suppressed the expression of endothelial NO synthase and sarcoplasmic reticulum Ca(2+)-ATPase mRNA (P<0.05). FR173657 also upregulated collagen type I and III mRNA (P<0.05) and increased the total amount of cardiac collagen deposits (P<0.05) in left ventricle compared with that in the enalapril-treated group. In conclusion, endogenous bradykinin contributes to the cardioprotective effect of ACE inhibitor, improving left ventricular diastolic dysfunction rather than systolic dysfunction, via modification of NO release and Ca(2+) handling and suppression of collagen accumulation.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Blood Pressure; Bradykinin; Bradykinin Receptor Antagonists; Calcium-Transporting ATPases; Collagen Type I; Collagen Type III; Diastole; Dogs; Enalapril; Gene Expression Regulation; Heart Failure; Hemodynamics; Hypotension; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Quinolines; RNA, Messenger; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Time Factors; Ventricular Function, Left