Captopril Treatment Improves the Sarcoplasmic Reticular Ca2+Transport in Heart Failure Due to Myocardial Infarction

Although captopril, an angiotensin-converting enzyme (ACE) inhibitor, has been shown to exert a beneficial effect on cardiac function in heart failure, its effect on the status of sarcoplasmic reticulum (SR) Ca2+transport in the failing heart has not been examined previously. In order to determine whether captopril has a protective action on cardiac function, as well as cardiac SR Ca2+-pump activity and gene expression, a rat model of heart failure due to myocardial infarction was employed in this study. Sham operated and infarcted rats were given captopril (2 g/l) in drinking water; this treatment was started at either 3 or 21 days and was carried out until 8 weeks after the surgery. The untreated animals with myocardial infarction showed increased heart weight and elevated left ventricular end diastolic pressure, reduced rates of pressure development and pressure fall, as well as depressed SR Ca2+uptake and Ca2+-stimulated ATPase activities in comparison with the sham control group. These hemodynamic and biochemical changes in the failing hearts were prevented by treatment of the infarcted animals with captopril. Likewise, the observed reductions in the SR Ca2+pump and phospholamban protein contents, as well as in the mRNA levels for SR Ca2+pump ATPase and phospholamban, in the failing heart were attenuated by captopril treatment. These results suggest that heart failure is associated with a defect in the SR Ca2+handling and a depression in the gene expression of SR proteins; the beneficial effect of captopril in heart failure may be due to its ability to prevent remodeling of the cardiac SR membrane.