【摘要】 本验实采用剂量率分别为7.8、15.1、31.0和61.0×10^-3mGy/min的⁶⁰Coγ线预先照射小鼠,持续20h,使累积剂量分别达到9.3、18.2、37.2和72.9mGy。从而诱发了小鼠骨髓细胞对再次大剂量（1.5Gy）急性照射的适应性反应。染色体分析表明,除最低剂量组外,各不同剂量的预先照射都使大剂量诱发的染色单体裂隙、断裂和无着丝点断片率明显降低于预期值（p<0.01）;而双着丝点加环型畸变率的降低无显著意义,在各不同剂量的预先照射组均可见到由随后大剂量诱发的畸变细胞率明显低于预期值（P<0.01）。染色体总畸变率和畸变细胞率与预期值的相对降低率有随预照射剂量的增加而降低的趋势。更多还原

【Abstract】 To test the effect of chronic pre-exposure of low dose ⁶⁰Co γ-rayson the induction of the adaptive response in vivo, four groups of micc were whole-bodyirradiated with different doses of 9.3, 18.2, 37.2, and 72.9 mGy at 7.8, 15.1,31.0, and 61.0×10^-3 mGy/min respectively, and then irradiated with 1.5 Gy γ-rays3 hours after the termination of pre-exposure. Mice bone marrow chromosome prepa-rations were made 24 hours later. The results showed that mouse bone marrow cellspretreated with 18.2, 37.2 and 72.0 mGy but not 9.3 mGy⁶⁰Co γ-rays yielded sig-nificant lower frequencies of chromatid aberration and acentric fragment induced bysubsequent high dose exposure than expected, but did not yield significant lower fre-ruencies of dicentric and ring. However significant reduction of aberrant cell frequen-cies induced by subsequent high does exposure were observed in all the four differentpretreated dose groups. The magnitude of the reductions of totai chromosnme aberrationand aberrant cell frequencies increased with the increasing of the pretreated doses.更多还原