Captopril attenuates pacing-induced acute heart failure by increasing total vascular capacitance

To study the effects of captopril pretreatment on vascular capacitance in acute heart failure, anesthetized splenectomized dogs were subjected to rapid right ventricular pacing (RRVP) at 250 beats/min for 60 min combined with an intravenous (i.v.) 20-ml/kg volume load of dextran 70 over 10 min. Captopril pretreatment [50 mg every 8 h for 3 days plus 0.5 mg/kg intravenously (i.v.) at induction of anesthesia] attenuated development of acute heart failure associated with RRVP, maintaining normal cardiac output (CO) and pulmonary capillary wedge pressures (PCWP). Total vascular capacitance after a volume load plus RRVP was higher in captopril-pretreated animals (129.8 +/- 3.2 vs. 100.4 +/- 4.8 ml/kg) owing to an increase in unstressed volume (118.6 +/- 3.1 vs. 88.4 +/- 5.6 ml/kg). Arterial capacity and pulmonary (central) vascular capacitance were also increased.