Studies on the Quantitative Biology of Hyperthermic Killing of HeLa Cells1

whereas others divide at least once before death. Cells selected for their capacity to survive prolonged periods of hyperthermia are killed at approximately the same rate during subsequent heat treatments as cells that had not been heated previously. Hyperthermic cell killing is reduced in cells that are heated in the presence of certain compounds that are inhibitors of DNA and protein synthesis. Fractionated dose experiments indicate that cells recover from sublethal hyperthermic damage. Furthermore, hyperthermic killing is at least a two-step process, and cells are capable of recovery from potentially lethal damage, particularly in the presence of cycloheximide and high levels of thymidine.