THE EFFECT OF NEPHRECTOMY ON ALDOSTERONE SECRETION IN THE CONSCIOUS SODIUM‐DEPLETED HYPOPHYSECTOMIZED SHEEP

Summary The effect of nephrectomy on aldosterone secretion was studied in 34 hypophysectomized sheep. Access to adrenal vein blood was obtained in 31 animals by the adrenal jugular bypass technique which involves left nephreetomy and cannulation of the left renal vein. The remaining 3 animals had cervical adrenal autotransplants. Sodium depletion by loss of parotid saliva was used as a stimulus to aldosterone secretion. In the majority of the bypass experiments and in each case in the sheep with adrenal transplants, nephrectomy resulted in aldostrerone secretion falling to the levels found in the sodium replete animal. There was little change 3–5hr. after nephrectomy, but by 10–12hr. aldosterone had decreased to the sodium replete range. In some experiments the fall took as long as 22hr. The findings were the same in animal with subtotal hypophysectomy as with complete hypophysectomy. Stopping infusion of sheep renin in does which elevated aldosterone secretion to comparable level in nephrectomized hypo‐physectomized animals resulted in a rapid fall within 2–3 hr. of aldosterone secretion to basal levels. In control experiments with nephrectomy of sodium repletete hypophysectomized sheep aldosterone secretion did not alter except where, after 12–24 hr., it rose coincident with a rise of plasma potasium concentration. The results showed that the presence of the kidney was essential for sustained aldosterone hypersecretion of the hypophysectomized sodium depleted sheep.