EFFECT OF COLD STRESS ON THE PHOSPHORUS METABOLISM OF THE ADRENAL GLAND

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Abstract
Observations were made on the effects of cold stress (3° ± 1 °C.) on the concentration of phosphorus and the incorporation of inorganic phosphate labelled with radioactive phosphorus (P32) into the following P-containing fractions in the rat: the inorganic P of the plasma, the inorganic P, 20-min. hydrolyzable P, and total acid-soluble P of the adrenal gland. With short periods of cold stress (2, 3, 6, 24 hr.) there was an increase in the relative specific activity of each of the adrenal fractions, greatest for an exposure of 2–3 hr. and least for 24 hr., with no significant change in the specific activity of the inorganic P of the plasma. With longer periods in the cold (2, 4, 8, 16 days), in addition to the usual increase in adrenal weight, there was an increase in the relative specific activity of each of the three acid-soluble P fractions of the adrenal. The increase in specific activity was not due to a decrease in the concentration of P in any of the fractions.Evidence is presented for the view that this change in the phosphorus metabolism of the adrenal can be interpreted in terms of an increase in the rate at which inorganic P32 passes across the cell membrane, i.e. from the extracellular to the cellular fluid. It is suggested that the change after a short (2–3 hr.) exposure to the cold is brought about by the stimulation of the adrenal cortex by endogenous ACTH from the pituitary. The change after longer (several days) exposures may be related to the function of the thyroid gland.