Furuno-Fukushi I, Aoki K, Matsudaira H
Division of Biology, National Institute of Radiological Sciences, Chiba-shi, Japan.
Radiat Res. 1993 Oct;136(1):97-102.
Induction of mutation to 6-thioguanine resistance was studied in cultured near-diploid mouse cells (m5S) in plateau and log phase after exposure to gamma rays at dose rates of 30 Gy/h, 180 mGy/h, or 13 mGy/h. In plateau-phase culture, lowering the dose rate from 30 Gy/h to 13 mGy/h resulted in an increase in cell survival and a marked decrease in induced mutation frequency. On the other hand, in the log-phase culture, the magnitude of the dose-rate effects was not as marked as in the plateau-phase culture, particularly within a dose range below 5 Gy. These results, together with those indicating the inverse dose-rate effects in growing mouse leukemia cells (Radiat Res. 115, 273-280, 1988), demonstrate the significant influence of cell growth that takes place during protracted irradiation, particularly for the induction of mutation.
研究了在剂量率分别为30 Gy/h、180 mGy/h或13 mGy/h的γ射线照射后，处于平台期和对数期的近二倍体小鼠细胞（m5S）中6-硫鸟嘌呤抗性突变的诱导情况。在平台期培养中，将剂量率从30 Gy/h降至13 mGy/h会导致细胞存活率增加，诱导突变频率显著降低。另一方面，在对数期培养中，剂量率效应的幅度不如平台期培养中明显，尤其是在低于5 Gy的剂量范围内。这些结果，连同那些表明在生长的小鼠白血病细胞中存在反向剂量率效应的结果（《辐射研究》115, 273 - 280, 1988），证明了在长时间照射期间细胞生长的显著影响，特别是对突变诱导的影响。
