Influence of Hypophysis on Pulmonary Injury Induced by Exposure to Oxygen at High Pressure and by Pneumococcus

Abstract

To determine factors responsible for the protection afforded by hypophysectomy against the adverse effects of O2 at high pressure (OHP), rats were exposed to O2 at 80 lbs. pressure for several min. once per day over several days. Hypophysectomy raised the threshold of onset of neuromuscular and central nervous reactions and diminished their severity. The severity of lung damage paralleled the severity of the neuromuscular reactions. Lungs of non-hypophysectomized rats were liver-like in color and consistency and sank in fixing soln. whereas hypophysecto-mized animals were strikingly less severely affected or remained clear in spite of more prolonged exposures. Cortisone admn. augmented the pulmonary damage induced by increased concn. of O2 at atmospheric pressure. The greater resistance of hypophysectomized animals to OHP is due in large part to the pulmonary protection which hypophysectomy affords. This increased resistance is due to the lowered production of adrenocortical factors and possibly also to the loss of thyrotropin. Hypophysectomy failed to provide similar protection against pulmonary injury induced by intratracheally inoculated pneumococcus.