Metabolic and Thermoregulatory Effects of Acute 60 Co Radiation in Myomorph Rodents

Abstract

The metabolic and thermoregulatory effects of sublethal /sup 60/Co gamma radiation were studied in the white-footed mouse (Peromyscus leucopus) and the wild house mouse (Mus musculus). In both species of mice the ionizing radiation caused higher metabolic rates, excess heat loss to the environment, and 1 to 3/sup 0/C lower body temperatures. Irradiated M. musculus experienced an 8% higher total metabolic rate than expected for controls, whereas irradiated P. leucopus registered a 20% higher total metabolic rate than expected. The effects of ionizing radiation were inversely proportional to activity; thermoregulation and metabolism were affected more when both species were at rest than when they were active. Irradiated P. leucopus became hyperthermic at an ambient temperature normally within thermoneutrality, and irradiated mice of both species became slightly hypothermic below thermoneutrality. Irradiated mice lost 25 to 30% more heat to the environment than controls. We suggest that blood circulation to peripheral tissues, or other hematological changes in irradiated mice, may bave occurred reducing the efficiency of thermal insulation.