Metabolic changes after non-lethal x-irradiation of rats. I. Carbohydrates, hormones

Male rats of the Wistar strain were fasted overnight prior to exposure to single total-body X-ray dose of 2.39 Gy (250 R). Irradiated and sham-irradiated rats were pair-fed for 5 days, in the next period they were fed ad libitum. The levels of corticosterone and immunoreactive insulin in serum, glucose in blood, glycogen in liver, heart and skeletal muscle were determined 1 and 6 h, 1, 2, 3, 7, 14, 28, and 38 days after irradiation and sham-irradiation. Irradiation of rats resulted, at one hour, in a decrease and, at two days, in an icrease in level of blood glucose. A marked increase in liver glycogen persisted from 6 h to 21 days after irradiation. The level of glycogen in the skeletal muscle was reduced at 6 h and increased on days 3 and 14. Heart muscle glycogen declined within the first 24 h and rose at 14 days after exposure. The kinetics of changes in the heart and skeletal muscle glycogen following non-lethal irradiation was similar and indicated an overlap of changes produced by fasting with those brought about by irradiation, particularly during the first week. Corticosterone in serum was markedly increased in rats at 24 and 72 h after irradiation compared to pair-fed controls. The serum insulin concentration did not change after irradiation, except for a single increase on day 21. Irradiation with non-lethal doses produced changes in the parameters of the carbohydrate metabolism studied, except for serum insulin, which reflected the changes in the nutrition regimen upon pair-feeding rather than the effect of ionizing irradiation.