放射線適応応答におけるマウスの骨髄死低減と出血抑制

抄録

It has been reported by the authors that priming X-irradiation of mice (ICR strain) with 0.3-0.5Gy two weeks before challenging irradiation induces radio-resistance (decrease in bone marrow death). This study was carried out to elucidate the mechanisms of the acquired radio-resistance. After challenging irradiation, peripheral blood cell counts were examined first, since bone marrow death has been thought to result from a functional disorder of bone marrow, suppression of hematopoiesis. But the blood cell counts of the thrombocytes, leukocytes and erythrocytes on days 14 and 15 after 5.5Gy were not influenced by the pre-irradiation. We next measured hemorrhage in the feces. It is reported to serve as a good indicator for evaluating the effectiveness of test therapeutic treatments on animals exposed to midlethal or sublethal doses. The pre-irradiation diminished the hemorrhage measured by quantitative determination of occult blood in the feces collected on days 10-12 after both 6.12 and 6.66Gy. On the other hand, coagulation time on day 12 was elongated by about 30% after challenging exposure to 5.2Gy, but the prolonged coagulation time was not recovered by the pre-irradiation. These studies suggest that some factor(s) that can possibly suppress hemorrhage might be produced in mice by pre-irradiation, but neither accelerates the recovery of hematopoiesis nor affects the coagulation time after the challenging irradiation.