Effect of Angiotensin on Renal Function of the Dog

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Abstract
Angiotensin (5 ng/kg/minand 50 ng/kg/min) was infused directly into the left renal artery of anesthetized dogs inorder to examine its effect onthe renal function. Urinary volume, creatinine clearance (GFR), PAH-clearance (RPF) and electrolyte excretion were decreased by infusion of a small dose of angiotensin. On the other hand extreme reductions of urinary volume, GFR, RPF and electrolyte excretion were observed immediately after the beginning of angiotensin infusion in a large dose, and were followed by gradual increases in these parameters during the administration of angiotensin (tachyphylaxis). In 4 out of 6 cases, urinary volume and Na excretion surpassed the control values with an increased extraction fraction of Na. These results suggested that angiotensin affected the renal function mainly through 2 mechanisms: Firstly, the vasoconstrictive action of angio-tension on the renovascular system causes decrease in urinary output, and secondly the direct action on the tubular system causes natriuresis.