PHARMACOLOGICAL EVALUATION IN CONSCIOUS DOGS OF FACTORS INVOLVED IN THE RENAL VASODILATOR EFFECT OF CAPTOPRIL

  • 1 January 1981
    • journal article
    • research article
    • Vol. 219  (3) , 646-650
Abstract
The roles of the blockade of formation of angiotensin II and prostaglandins in the renal vasodilator effect of captopril in conscious salt-replete dogs were examined. Blood pressure was recorded from an indwelling catheter, and renal blood flow (RBF) was measured with an electromagnetic flowmeter and an implanted flow probe. Plasma renin activity was measured by radioimmunoassay. The effect of captopril (0.2 mg/kg i.v.) on RBF was compared in dogs given either saralasin (0.5 .mu.g/kg per min i.a. [intraarterial]) or indomethacin (5 mg/kg i.v.) with that in dogs given saline vehicle. Control plasma renin activity in these groups of animals before drug treatment ranged from 0.74-1.18 ng of angiotensin l per mil/h. Captopril decreased blood pressure from 102 .+-. 4 to 92 .+-. 4 mm Hg (P < 0.01) and increased RBF from 278 .+-. 23 to 345 .+-. 29 ml/min (25%) (P < 0.01) in saline vehicle-treated animals. In the presence of intrarenal infusion of saralasin, captopril did not increase RBF but decreased blood pressure slightly. Captopril still increased RBF by 18% in indomethacin-treated dogs. Evidently, the renal vasodilator effect of captopril in conscious salt-replete dogs is mainly due to the blockade of angiotensin II formation. The renin-angiotensin system appears to have an influence on renal vascular tone even under these basal conditions.