It has been shown that the adrenal cortex gives a diminished secretory response to exogenous corticotrophin (ACTH) 2–3 h after exposure to moderate doses of ionizing radiation (Ungar, Rosenfeld, Dorfman & Pincus, 1955; Shima & Matsuba, 1963). The present paper describes observations made on adult dogs for up to 14 days after X-irradiation of one adrenal gland.
Adult mongrel dogs weighing 10·3–18·5 kg were used. Under sodium pentobarbitone anaesthesia, the left adrenal gland was exposed by the left lumbar route and irradiated with 2000 R of X-rays. The X-ray characteristics were: 180 kV peak, 20 mA, focus—surface distance 37 cm, filtration of 0·5 mm Cu and 0·5 mm Al, and half-value-layer 1·0 mm Cu. Dose-rate to the adrenal gland was approximately 130 R/min. Observations were carried out at 2, 7 and 14 days after irradiation.
On the day of observation, each animal was injected s.c. with 0·1 mg dexamethasone-21-phosphate/kg. One