Transformation and cell killing by X-rays and anisotonic treatments in C3H-10T1/2 cells: Effect on damage fixation and repair

C3H-10T1/2 cells were exposed to 0.05 or 1.5 mol/L NaCl solutions and irradiated before or during the salt exposure time. The 0.05 mol/L NaCl treatment by itself was not toxic and induced no transformation while the 1.5 mol/L treatment was toxic and slightly increased the transformation frequency for prolonged exposure times. When cells were irradiated in the presence of 0.05 mol/L NaCl, radiosensitization occurred and was characterized by increased cell killing and increased transformation frequency while cells irradiated in the presence of 1.5 mol/L NaCl underwent radioprotection which was characterized by decreased cell killing and transformation. Exposure to 0.05 mol/L or 1.5 mol/L NaCl after irradiation resulted in increased cell killing and transformation as a function of NaCl exposure time at 370C. This effect was greater for the 1.5 mol/L treatment compared to the 0.05 mol/L treatment. Incubation at 370C between the X-ray exposure and the NaCl treatment resulted in increased survival levels and decreased transformation frequencies. These data demonstrate that C3H-10T1/2 can repair potentially lethal and potentially transformed damage after irradiation and that this damage is expressed by anisotonic treatment