Species differences in altitude tolerance following X-irradiation

¹ Division of Biological and Medical Sciences, U.S. Naval Radiological Defense Laboratory, San Francisco, California

The relationship between altitude tolerance and food consumption was investigated in irradiated and nonirradiated animals of several species. Food consumption was measured for 3 days following a mid-lethal dose of x-irradiation to assess the degree of postirradiation anorexia. Seventy-two hours after irradiation those animals, as well as ad libitum-fed and food-deprived nonirradiated animals were exposed to a simulated altitude tolerance test. The mortality produced in 4 hours was used as the criterion of hypoxic tolerance for each species. Irradiated rabbits and rats exhibited a severe decrease in food consumption and an increased hypoxic tolerance. Food consumption of mice was depressed during the 3 days following irradiation although the effect was much less than that observed for rats and rabbits. Guinea pigs and hamsters exhibited only a slight decrease in food consumption with recovery occurring after 24 hours. Mice, guinea pigs and hamsters did not exhibit a significant increase in hypoxic tolerance 3 days after radiation exposure. When nonirradiated rabbits, rats, mice and guinea pigs were food deprived, the hypoxic tolerance was significantly increased in all species.