Comparative effects of perindopril with enalapril in rats with dilated cardiomyopathy

Angiotensin-converting enzyme inhibitors have been shown to reduce morbidity and mortality in patients with heart failure. The angiotensin type-1 blocking and cardioprotective properties of perindopril and enalapril were studied in a rat model of dilated cardiomyopathy after autoimmune myocarditis. Enalapril at 20 mg/kg showed the same angiotensin type-1 blocking action as perindopril at 2 mg/kg in rats with heart failure. Twenty-eight days after immunization, surviving Lewis rats (90/120 = 75%) were divided into six groups and administered perindopril at 0.02, 0.2 and 2 mg/kg per day (Groups P0.02, P0.2 and P2), enalapril at 2 and 20 mg/kg per day (Groups E2 and E20) or vehicle alone (Group V, all groups n = 15). After oral administration for 1 month, four of 15 (27%) rats in Group V, and two (13%) in Groups P0.02 and E2 died. None of the animals in Groups P0.2, P2 and E20, or normal rats (Group N) died. Although both angiotensin-converting enzyme inhibitors improved ventricular function in a dose-dependent manner, the left ventricular end-diastolic pressure and area of myocardial fibrosis were lower, and +/- dP/dt was higher in Group P2 (4.9 +/- 0.6 mmHg, 7.5 +/- 1.4% and +2651 +/- 254/-2622 +/- 189 mmHg/s, respectively) than in Group V (16.7 +/- 1.3, 36 +/- 2.6 and +2659 +/- 176/-2516 +/- 205, respectively) and Group E20 (7.5 +/- 2.5, 15.6 +/- 2.0 and +2018 +/- 110/-2097 +/- 102, respectively). Although the expression levels of transforming growth factor-beta1 and collagen-III mRNA in Group V (36.3 +/- 5.7 and 157.6 +/- 12.7%) were significantly higher than those in Group N (19.6 +/- 3.0 and 65.2 +/- 1.5%, both p < 0.01), they were reduced in Group P2 (21.4 +/- 5.9 and 75.2 +/- 9.3%, both p < 0.01). These results suggest that although enalapril can block increases in blood pressure caused by circulating angiotensin type-1, perindopril at 2 mg/kg may confer greater protection than enalapril at 20 mg/kg against injury from the renin-angiotensin system in heart failure.