The effect of hypo- and hypertonic nacl solutions on cellular damage resulting from combined treatments of heat and x-rays

The exposure of Chinese hamster V79 cells to 0·05 or 1·5 M NaCl immediately after combined treatment with heat and X-rays resulted in fixation of potentially lethal damage. The synergistic damage resulting from the interaction of heat and X-rays responded to anisotonic treatment like X-ray damage when heating was at 44·0 or 45·0°C and like heat damage when heating was at 41·5 or 42·0°C. When anisotonic treatment was given before heat plus X-ray exposure, sensitization occurred but the differences between heating at 42·0 and 45·0°C were not as large. Incubation at 37°C between heat and X-ray treatments or between X-ray and heat treatments resulted in recovery as manifested by a decrease in the fixation of damage by subsequent anisotonic treatment. Recovery was also observed when cells were incubated at 37°C between the combined exposure to heat plus X-rays and the anisotonic treatment. These data imply that the lesions produced by heat plus X-ray treatments, which are susceptible to salt fixation, can be repaired.