The influence of dose rate on the lethal and mutagenic effects of X-rays in proliferating L5178Y cells differing in radiation sensitivity.
The lethal and mutagenic effects of ionizing radiation delivered at high (53 Gy/h) and low (0.02 Gy/h) dose rates were measured in two closely related strains of mouse lymphoma L5178Y cells differing in radiation sensitivity (LY-R and LY-S). Strain LY-R was more resistant to the lethal effects of radiation than strain LY-S when exposed at either the high or low dose rate. The survival of strain LY-R was markedly enhanced by the reduction in dose rate. The dose-rate dependence of the survival of strain LY-S was less clear, because of the biphasic nature of its survival curve following low dose-rate radiation. However, if the initial slope of the low dose-rate survival curve is compared to the slope of the high dose-rate survival curve for strain LY-S, only a slight increase in survival at the low dose rate is apparent. Although more sensitive to the lethal effects of radiation, strain LY-S was less mutable at the hypoxanthine/guanine phosphoribosyl transferase locus by both low dose-rate and high dose-rate radiation than strain LY-R. Little dose-rate dependence was exhibited by either strain with regard to the mutagenic effects of radiation. Thus, for strain LY-R, which showed marked dose-rate dependence for survival but not for mutation, the ratio of mutational to lethal lesions was much greater following exposure to low dose-rate than to high dose-rate radiation.
D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D066298:In Vitro Techniques; D007940:Leukemia L5178 / Q000473:pathology*; D007942:Leukemia, Experimental / Q000473:pathology*; D051379:Mice; D009154:Mutation; D011831:Radiation Genetics; D011836:Radiation Tolerance; D013997:Time Factors