ERYTHROPOIESIS IN MICE EXPOSED TO CONTINUOUS WHOLE-BODY IRRADIATION OF GAMMA-RAYS

The erythropoietic effects of continuous γ-irradiation with a daily regime of 0.029, 0.083 and 0.374 Gy were studied in mice. Irradiation was performed with 137Cs γ-rays for 22 hr/day. The length of irradiation time varied from 3 to 112 days. Erythropoiesis was investigated on the basis of clearance of 59Fe from the circulation and of incorporation of 59Fe into circulating erythrocytes and erythropoietic tissue. A chemical method for the separation of heme and nonheme iron-containing fractions was employed to examine the uptake of 59Fe into both the heme and nonheme iron fractions. Daily exposure to 0.029 and 0.083 Gy caused no significant changes in erythropoiesis. Daily exposure to 0.374 Gy caused some significant changes in erythropoiesis. On day 7 of continuous irradiation, the amount of 59Fe incorporated into erythrocytes decreased, but the values returned to normal on day 14 and 28 of continuous irradiation, indicating recovery within erythropoietic tissues at earlier time. On day 56, depressed incorporation of 59Fe into erythrocytes with normal rate of disappearance of 59Fe from the circulation and increased heme level of 59Fe in the femoral marrow were observed. Results observed on day 56 may suggest the possibility of ineffective erythropoiesis during the continuous irradiation. On day 112, some mice showed almost the same changes in erythropoiesis as those mice exposed to acute X-rays radiation. Copyright © 1988 Japan Radiation Research Society.