Effect of Dose and Partial-Body X-Irradiation on the Lethality Response of Rats to Low Temperature

It was demonstrated previously that the median survival time (MST) of rats exposed to low temperature was decreased when cold challenge was immediately preceded by whole-body x-irradiation. To determine if the decreased tolerance of irradiated rats to cold was the result of radiation damage to specific sites, partial-body irradiation studies were conducted. Survival times at -17°C were determined for groups of juvenile male rats that were exposed to cold within 130 minutes after x-irradiation (1000 rad) of the head, body, hindquarters, or the whole body. The MST's of the head, body, and whole-body irradiated groups were similar, and were significantly less than that of the nonirradiated control group. No radiation-induced reduction in survival time in the cold was observed in the hindquarters-irradiated group, even though the irradiated mass was about twice that of the head group. After a radiation dose of 500 rad, cold tolerance was equally reduced by body or whole-body irradiation, but not affected when...