Correlation of colony forming ability of mammalian cells with potassium content after hyperthermia under different experimental conditions.

When the potassium content of LM mouse fibroblasts was determined 16 hr after a heat treatment, a correlation was found between the concentration of potassium in the cell population and the level of cellular survival. When the cells were made thermotolerant, the degree of acquired heat resistance corresponded to a higher level of residual potassium. Also the degree of heat protection by erythritol corresponded to a higher level of residual potassium in the cells, while heat sensitization by procaine resulted in a lower level of potassium. It is concluded that the amount of residual potassium in these cells measured 16 hr after heat treatment may be considered as a suitable index for cell survival after hyperthermia treatment under different conditions.