Repair of radiation induced damage--dependence on oxygen and energy status.

Repair of radiation-induced sublethal damage by Chinese hamster V-79 cells is studied under conditions of different pO2 (15 ppm to 21%) and cellular energy status. Cellular ATP content and energy charge are drastically reduced when cells are deprived of both oxygen and nutrient. Both indices are within normal range when cells are provided with nutrients or trace levels of oxygen (300 ppm). When deprived of nutrient, hypoxic (15 ppm O2) cells do not repair SLD, while cells in 300 ppm O2 do. Thus, cellular SLD repair appears to be dependent on cellular energy status which in turn is sensitive to oxygen concentration. Relatedly, nutrient deprived hypoxic cells are sensitized to radiation with storage under 23 degrees C, a phenomenon which may stem from a decrease of endogenous glutathione content.