Protection against Heat-induced Cell Killing by Polyols in Vitro1

The polyols erythritol and adonitol reduced 45°heat killing in asynchronous Chinese hamster ovary cells. Heat protection by glycerol and erythritol increased with the apparent intracellular concentration, as inferred from cell volume measurements, and the number of hydroxyl groups per alcohol molecule. The nonlin ear tetrahydroxy alcohol pentaerythritol did not protect but sen sitized to heat killing. On cell survival curves, the reduced cell killing of protected cells was expressed by an increased 00 for the pentahydroxy alcohol adonitol (0.3 M), whereas equimolar concentrations of glycerol increased primarily the D, (quasithreshold dose) with little increase in D0. The distribution of Chinese hamster ovary cells within the cell cycle was unaffected by the presence of 0.3 M glycerol in the culture medium. However, the polyols erythritol and sorbito! caused a small but significant loss of cells from the heat-resistant d compartment. The cell cycle redistribution with prolonged incubation (6 hr) in polyol-supplemented medium is expected to increase the heat sensitivity of the perturbed cell population; the observed heat protection by polyols suggests that heat resistance in the presence of polyols is not an artifact of an asynchronous cell system. Instead, the data identify a family of heat-protective compounds that may occur naturally in mammalian cells.