Adrenocortical function in rats chronically exposed to high altitude.

In rats exposed to a simulated altitude of 5,486 m for 3 mo, pituitary and adrenal glands hypertrophied and plasma levels of corticosterone increased more than threefold over sea-level controls. The in vitro rates of corticosterone production by the quartered adrenal gland were significantly enhanced, but the responsiveness of the adrenal gland to ACTH remained normal.