EFFECT OF ADRENOCORTICOTROPHIC AND GROWTH HORMONES ON ALDOSTERONE PRODUCTION AND PLASMA RENIN ACTIVITY IN CHRONICALLY HYPOPHYSECTOMIZED SODIUM-DEFICIENT RATS

Abstract

SUMMARY Hypophysectomy abolishes the aldosterone secretory response to sodium deficiency in rats. Sodium deficiency causes a significant increase in plasma renin activity in chronically hypophysectomized rats which is of the same order as that found in intact animals. Long-term treatment with either adrenal maintenance doses of corticotrophin (ACTH) or with growth hormone (STH) did not affect the low rate of aldosterone production of hypophysectomized rats on a sodium-deficient diet. However, ACTH and STH given simultaneously restored the aldosterone secretory response to sodium deficiency in chronically hypophysectomized rats. The plasma renin activity of hypophysectomized rats on a sodium-deficient or a normal diet remained unaltered during treatment with either ACTH or STH or with the two hormones given simultaneously. This was also reflected in the systolic blood pressure of rats which, under the conditions used, did not change when the animals were sodium-deficient, or after hypophysectomy or hormone treatment. These results indicate that the effect of STH, in restoring the aldosterone secretory response to sodium deficiency in the presence of adrenal maintenance doses of ACTH in chronically hypophysectomized rats, is independent of changes in the renin-angiotensin system.