The Reaction of the Adrenal Cortex to Low Atmospheric Pressure *

Numerous investigators have reported that anoxia produces an activation of the adrenal medulla,4' 10, 11, 16, 25, 40, 41, 50, 57 but only recently has it been revealed that the adrenal cortex is also activated when an animal is exposed to low atmospheric pressure. Evans reported17' 18 in 1934 and 1935 a striking increase in blood sugar and liver glycogen in rats exposed to one-half atmospheric pressure. This did not occur after extirpation of the adrenal cortex. He concluded, therefore, that upon exposure to anoxia the adrenal cortex is activated, and that its secretion caused the observed alterations in carbohydrate metabolism. FitzGerald2' confirmed these findings. Giragossintz and Sundstroem24 published a brief report in 1937, in which they stated that exposure of an animal to low pressures results in disturbances similar to those characteristic of adrenal insufficiency. They found adrenalectomized rats to require about 20 times the sealevel maintenance dosage of extract while exposed to a simulated altitude of 24,000 feet. Armstrong and Heim' observed marked hypertrophy of the adrenal glands in animals exposed daily to an altitude of 18,000 feet. Lewis, Thorn, Koepf, and Dorrance43 have recently reported an extensive study of the relationship of acute anoxia to the adrenal cortex in which they confirmed, in part, the observations of Evans. They concluded that during the initial phase of anoxia there is an increased utilization of carlbohydrate which stimulates the adrenal cortex, resulting in the observed alterations. in carbohydrate metabolism. We have reinvestigated the role played by the adrenal cortex in the adjustment of the organism exposed to low atmospheric pressure. We have studied in rats and dogs the effects of anoxia upon the adrenal size, the minimum required amounts of adrenal cortical