The effect of GSH depletion on thermal radiosensitization

Depletion of intracellular glutathione (GSH) increased aerobic thermal radiosensitization in Chinese hamster ovary (CHO) cells gamma irradiated and heated at 42 degrees C. The GSH concentration was decreased to various stable levels by exposure to increasing concentrations of diethylmaleate (DEM). Analysis of dose-response curves indicated that GSH depletion affected thermal sensitization and thermal radiosensitization at 42 degrees when greater than 95% of the GSH had been depleted. GSH depletion also increased the fixation of radiation damage. For example, survival after 10 Gy decreased from 0.012 to 0.006 if CHO cells were incubated in 100 microM DEM at 37 degrees for 2 hrs after irradiation. The results show that GSH might be an important agent for the protection of cells against thermal enhancement of radiation damage.