Adrenocortical Response to Single and Repeated Exposure to Oxygen at High Pressure

Abstract

Exposures of rats to O2 at pressures of from 30-90 lb. (OHP) increased adrenal size, weight, and changed its color, indicative of hyperactivity. Histological changes were typical of non-specific stress conditions; the zona fasiculata was thickened, its constituent cells hypertrophied, and lipoid content reduced. OHP evokes this adrenocortical reaction through, (a) secondary stress conditions such as strong muscular contractions, convulsive seizures and pulmonary damage induced by OHP, and (b) less obvious but more direct or primary effects possibly such as the elevation of tissue CO2, enzyme poisoning and a resultant condition simulating stress of low O2 administration. These primary effects can operate alone and independently of the secondary stress conditions which they probably initiate. Although the histological data fail to show that OHP per se is a unique type of stress, other evidence indicates it does possess some peculiarities.