Cardiac and renal effects of omapatrilat, a vasopeptidase inhibitor, in rats with experimental congestive heart failure

Omapatrilat (OMP) is a novel mixed inhibitor of angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP), the enzyme that metabolizes natriuretic peptides. Congestive heart failure (CHF) is characterized by excessive sodium retention, attributed to both an excessive effect of angiotensin II and diminished responsiveness to natriuretic peptides. In this study, we examined the acute and chronic renal and cardiac effects of OMP in rats with compensated [urinary sodium excretion (UNaV) > 1,200 μeq/day] and decompensated (UNaV < 100 μeq/day) CHF, induced by a surgical aortocaval fistula (ACF). Bolus injection of OMP (10 mg/kg) to sham controls produced significant diuretic and natriuretic responses [UNaV increased from 0.67 ± 0.19 to 3.27 ± 1.35 μeq/min, P < 0.05; fractional sodium excretion (FENa) increased from 0.23 ± 0.06 to 0.95 ± 0.34%, P < 0.01] despite a significant decline in blood pressure (BP). Rats with compensated CHF displayed blunted diuresis and natriuresis to this dose of OMP b...