QUINAPRILAT INCREASES TOTAL BODY VASCULAR COMPLIANCE IN RATS WITH MYOCARDIAL INFARCTION

To test whether quinaprilat,a new angiotensinconverting enzyme inhibitor,has any venous effect,itsimmediate effects were measured on mean circulatoryfilling pressure(MCFP),intravascular volume and to-tal body vascular(i.e.,venous)compliance in consciousrats with mild congestive heart failure induced bycoronary artery ligation.MCFP was determined by in-flating a right atrial balloon to arrest the circulationinstantly and temporarily.Total body vascular compli-ance was derived from total circulatory pressure-vol-ume relationships as determined by seriesmeasurements of MCFP with different intravascularvolume status.In 8 rats with mean infarct size of26±4%,30-minute infusion of quinaprilat(0.1mg/kg/min)decreased both mean arterial andcentral venous pressures by 8 mmHg and 0.7 mmHg,respectively(P<0.02);heart rate,MCFP,hematocritand blood volume remained unchanged.Comparedwith control vehicle infusion,quinaprilat increased thetotal body vascular compliance(2.09±0.12 vs 2.69±0.23ml/kg/mmHg;P<0.05)and decreasedextrapolated unstressed circulating volume(34.96±1.10 vs 28.53±2.55ml/kg;P<0.02).These datasuggest that quinaprilat produces possible venodilationthrough immediately improved total body vascularcompliance thereby reducing cardiac preload in this ratmodel of chronic heart failure.