Effect of Pure Oxygen at Reduced Pressures on Metabolic Changes in Mice Living under Simulated Bio-Satellite Conditions

摘要

Metabolic changes were studied in mice that were maintained on air at simulated 14,000 or 20,000 ft. altitude, or on pure oxygen at simulated 30,000 ft. for a period of 3 to 5 weeks. The mice were removed from this situation only long enough each day to be fed, watered, and cleaned. The 'equivalence' between protein catabolized and carbohydrate synthesized was determined in mice injected subcutaneously with 5 mg. cortisone acetate and subsequently fasted for 17 hours. For control mice and those exposed to pure oxygen at 30,000 ft. and 34,000 ft. the equivalence was 92, 90, and 98 percent, respectively; animals on air at 14,000 ft. and at 20,000 ft., 46 and 37 percent. In all mice, the protein catabolized in response to cortisone was the same statistically, but the carbohydrate synthesized varied. Survival in mice under hypoxic conditions (14,000 to 20,000 ft.), after endotoxin injection, amounted to 35 to 46 percent; while control animals and animals kept on pure oxygen at 34,000 ft. and given endotoxin showed 84 to 86 percent survival. Low barometric pressure apparently causes an increase in urea formation about 50 percent above control levels. A sublethal injection of endotoxin drops it to normal, but these animals contain an increase in total body NPN equal to the decrease in urinary NPN. Altitude-exposed mice respond to an injection of ACTH with less increase in urinary nitrogen excretion than control mice. Their adrenals contain less cholesterol than those of normal animals, and the cholesterol decreases less after ACTH. (Author)