INFLUENCE OF STRESS ON PLASMA AND ADRENAL CORTICOSTERONE LEVELS IN RATS WITH INTACT AND REGENERATING ADRENALS1

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Abstract
A study was made of the ability of the regenerating adrenal to secrete corticosterone in response to stress as part of our investigation of the possible role of regenerating adrcnocortical tissue in the genesis of adrenal-regeneration hypertension. Response to stress was measured in rats bearing intact adrenals, two regenerating adrenals, and one regenerating adrenal. Groups of 20 such animals were given water or 1% saline to drink, or unincphrectomized and given 1% saline. Twenty-one days after enucleation, the rats were decapitated under “resting” and “stressed” conditions. Corticosterone in plasma and adrenal pools was measured by an isotopic dilution technique using corticosterone-4-C14 and a fluorometric procedure. Plasma level of all groups of unstressed rats were essentially the same, ranging from 3 to 7 ¼g corticosteronc/100 ml. In rats with intact adrenals, plasma corticosterone levels were directly related to the amount of steroid in the glands under resting and stressed conditions. Regenerating adrenals contained from 2 to 4 times more corticosterone under resting conditions than could be expected from plasma levels. Rats with two regenerating adrenals responded to stress with higher peripheral plasma levels of corticosterone than did animals with one regenerating gland, but these values were always less than those of the controls. Neither salt load, nor salt load and uninephrectomy changed the functional response of regenerating adrenal tissue to stress.