The effects of captopril (SQ14,225) on the systemic and coronary haemodynamics of the intact anaesthetized dog.

1. The effects of Captopril (SQ14,225), an inhibitor of angiotensin-converting enzyme, given intravenously in a dose of 0.3 mg/kg ws studied in intact anaesthetized dogs. 2. The drug caused a decrease in systemic and pulmonary arterial mean pressures, an increase in cardiac output, and hence a decrease in calculated systemic and pulmonary vascular resistances. A sustained tachycardia also occurred. 3. A minor, transient increase in coronary sinus flow was recorded, with a sustained decrease in calculated coronary vascular resistance. 4. No change was found in cardiac oxygen metabolism nor in calculated cardiac efficiency. 5. The plasma renin values increased in the control animals and those given the drug.