Effect of bleeding on recovery of erythropoiesis in mice after irradiation

The radioprotective effect of bleeding was studied by depleting 0.4 ml of blood immediately after whole body irradiation. As the indicator in this experiment, 30-day survival rate was used. To analyse the effect of bleeding, erythropoietic recovery after irradiation was examined. Before these experiments, erythropoietic activity after the depletion was examined in non-irradiated mice. Also, radioactive iron uptake was measured in the femur and spleen as an indicator of erythropoietic activity in both irradiated and non-irradiated groups. An increase in the 30-day survival rate was noted: 40% in the group with blood depletion after 700 R irradiation, but only 15% in the group without blood depletion. In blood depleted mice, marked erythropoietic activity was observed in the spleen, but this activity was not increased in the femur bone marrow. Gradual and relatively early increase in iron-59 uptake was observed immediately after irradiation in the blood-depleted mice but not in those with irradiation alone. This phenomenon indicated early recovery of erythropoietic repopulation in the spleen. The mean number of endogenous spleen colonies was 13 and 27 respectively, in the mice without and with blood depletion immediately after 750 R irradiation. (author)