Captopril and the maintenance of blood pressure after sinoaortic denervation in the rabbit.

1. At a dose of 1 mg/kg intravenously, captopril lowered blood pressure in conscious rabbits, that had undergone denervation of sinoaortic baroreceptors, but had no effect on heart rate. In sham-operated controls, this dose caused only an increase in heart rate. 2. In the same experiments, captopril caused a substantial inhibition of plasma angiotensin converting enzyme (CE) activity of rapid onset and gradual decline over 2 to 3 h. The time course of recovery of blood pressure and plasma CE activity were similar. 3. Saralasin, by intravenous infusion, lowered blood pressure in sinoaortic rabbits but to a smaller extent than captopril. 4. The fall in blood pressure observed after captopril is not dependent on the integrity of baroreceptor afferents.