PHOSPHORUS METABOLISM OF THE ADRENAL GLAND EFFECT OF HYPOPHYSECTOMY AND ADMINISTRATION OF ACTH ON INCORPORATION OF P32 INTO INORGANIC PHOSPHATE

Abstract

In confirmation of the work of others, the concentration of inorganic phosphate (P) in the plasma of hypophysectomized rats was found to be less than that in the plasma of control animals. Hypophysectomy caused no significant change in the concentration of inorganic P in the adrenal gland or liver. A single intraperitoneal injection of each of two preparations of ACTH failed to cause any significant change in the concentrations of inorganic P in plasma, adrenal, or liver.The specific activity of the inorganic P in the plasma of hypophysectomized rats after an intraperitoneal injection of inorganic P labelled with P32 was greater than that in the control animals. Hypophysectomy caused a decrease in the specific activity of the inorganic P of the adrenal gland relative to that of the inorganic P of the plasma. Each of the two preparations of ACTH, given to the hypophysectomized animals as a single intraperitoneal injection 20 hr. before killing, restored the relative specific activity of the inorganic P of the adrenals to normal values. When the ACTH was administered six hours before killing, one of the preparations (ACTH A) caused an increase in the relative specific activity of the inorganic P of the adrenals, but a second preparation (ACTH C) was without significant effect.The increase in the specific activity of the inorganic P of the plasma comes on slowly (quite small two days after hypophysectomy), whereas the decrease in the relative specific activity of the inorganic P of the adrenal gland comes on rapidly (maximal two days after hypophysectomy). For this reason, at longer time intervals after hypophysectomy (greater than six days) the absolute activity of the acid-soluble P of the adrenal, i.e. the activity not referred to that of the inorganic P of the plasma, was greater in hypophysectomized animals, and not less, as reported by other workers. The activity of this fraction is less in hypophysectomized animals only if the observations are made at short time intervals after removal of the pituitary. Evidence is presented for the view that the increase in the specific activity of the inorganic P of the plasma is the result of changes brought about by a deficiency of growth hormone, whereas the decrease in the relative specific activity of the adrenal is due to a deficiency of ACTH.