Abstract
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 degrees C and like heat damage when heating was at 41.5 or 42.0 degrees 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 degrees C were not as large. Incubation at 37 degrees 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 degrees 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.