The effect of hyperthermia on intracellular K+ in Chinese hamster ovary cells

The effect of hyperthermia on intracellular K+ concentrations was studied in Chinese hamster ovary (CHO) cells in vitro, using a flame photometer. Intracellular K+ concentrations decreased with increasing exposure time at temperatures from 40 degrees C to 45 degrees C. The decrease in K+ concentrations preceded any loss of reproductive capability at 43 degrees C and also occurred at the non-lethal temperature of 40 degrees C. Prolonged exposure to 45 degrees C resulted in an irreversible decrease in K+ concentrations. The decrease in K+ concentrations at elevated temperatures was not accounted for by changes in cell volume, loss of cells or failure of the Na+/K+ pump.