低水平辐射诱导的细胞遗传学适应性反应

先用0.01GY x-射线(剂量率:0.01GY/分)体外照射人、兔外周血,经不同时间后再用1.5GY X-射线(0.44GY/分)照射,发现在G_0、G_1、S和G_2期受0.01GY X-射线照射后再给大剂量照射者,其染色体畸变率明显低于单纯受1.5GY X-射线照射组(P<0.01)。这一适应性反应能持续3个细胞周期,在接受小剂量照射后超过3个细胞周期再受大剂量照射者,染色体畸变率未见减少。若在第三细胞周期以后再次给予小剂量照射,可再次诱导适应性反应。用小鼠整体小剂量照射后骨髓细胞和生殖细胞亦出现这种适应性反应。另外也探讨了不同剂量和不同剂量率的预先照射对适应性反应的影响。

Cytogenetic Adaptive Response Induced by Low Dose Radiation

Human and rabbit peripheral blood lymphocytes were irradiated in vitro with 1.5 Gy x-rays after exposure to 0.01 Gy of x-rays (dose rate: 0.01 Gy/min). The frequency of chromosome aberration in the cells pre-exposed to 0.01 Gy of x-rays at Go, Gl, S and G2 phases of cell cycle respectively was markedly lower than that in the cells irradiated with 1.5 Gy alone (P<0.01). This adaptive response would last for 3 cell-cycles, beyond which the damage of the chromosome following the second large dose occured with the same magnitude as that without a previous conditioning exposure. However, when the low dose was repeated affter the third cell cycle the adaptive response could be revived. Meanwhile, it was found that the adaptive response could be also induced in vivo in the bone marrow cells and germ cells of mice by low dose irradiation. In addition, the effect of dose rate of the first irradiation on the induced adaptive response was also studied.