Sampatrilat is a novel
vasopeptidase inhibitor that may offer a greater benefit than traditional
angiotensin-converting enzyme (
ACE) inhibitors in the treatment of chronic
heart failure (CHF). The present study was undertaken to determine whether
sampatrilat improves hemodynamic function and cardiac remodeling through a direct action on the failing heart in rats with CHF following left coronary artery
ligation (CAL).
Sampatrilat (30 mg/kg a day) was administered orally to the animals from the 1st to 6th week after the operation.
Sampatrilat reduced the mortality of the rats with CAL (20 versus 57% for untreated rats). Treatment with
sampatrilat for 5 weeks suppressed tissue ACE and
neutral endopeptidase (NEP) activities.
Sampatrilat did not affect the arterial blood pressure, whereas it attenuated the CAL-induced increases in the left ventricular end-diastolic pressure, heart weight, and
collagen content of the viable left ventricle. To assess the direct effects of
sampatrilat on
collagen synthesis, we measured the incorporation of [(3)H]
proline into cultured cardiac fibroblasts.
Sampatrilat at concentrations that inhibited NEP activity in vitro augmented the
atrial natriuretic peptide-induced decrease in [(3)H]
proline incorporation by the cells. In addition,
sampatrilat prevented the
angiotensin I-induced increase in [(3)H]
proline incorporation, whereas
captopril did not. The results suggest that long-term treatment with
sampatrilat regresses cardiac remodeling in rats with CAL, which is associated with improvement of hemodynamic function. The mechanism by which
sampatrilat improved cardiac remodeling may be attributable to the direct inhibition of cardiac
fibrosis, possibly acting through the cardiac
natriuretic peptide system.