[Modification of organ perfusion by calcium blocker and converting enzyme inhibitor in the conscious rat with heart failure].

The present study examined the regional vascular effects (radioactive microspheres) of converting-enzyme inhibition (captopril, 1 mg/kg) and calcium-antagonism (diltiazem, 1 mg/kg) in a rat model of cardiac failure due to large myocardial infarction (n = 18, infarct size 40% of the left ventricle) both at rest and during submaximal treadmill exercise. Diltiazem increased renal, gastrointestinal, coronary and cutaneous blood flow at rest by 29%, 28%, 26% and 37% (p less than 0.05 each) and enhanced skeletal muscle blood flow during exercise by 16% (p less than 0.05). Captopril improved primarily renal and coronary blood flow at rest (by 59% and 23%, respectively, p less than 0.05) and reduced vascular resistance in the gastrointestinal bed by 25% (p less than 0.05) without significant effects in other circulatory beds. We conclude that the regional vascular effects elicited by converting-enzyme inhibition and calcium antagonism differ considerably in this animal model of congestive heart failure and may be clinically important. The favourable regional vascular profile of diltiazem deserves further clinical investigation.