Enhancement of Survival of X-Irradiated Mammalian Cells by the Uncoupler of Oxidative Phosphorylation, m-Chloro Carbonyl Cyanide Phenylhydrazone

Incubation with m-chloro carbonyl cyanide phenylhydrazone, an uncoupler of oxidative phosphorylation, prior to irradiation, markedly increased the survival of cells exposed to ionizing radiations. Similar results were obtained with two cell lines, one of human origin (LICH) and one of murine origin ( H₄). Growth-inhibited cells were more sensitive to the effects of the agent; the D₀ (inverse of the slope) of the survival curve for H₄ cells irradiated in the plateau phase of growth increased from 152 to 269 rad, whereas the D₀ for exponentially growing cells shifted from 154 to 180 rad. The agent had no influence on cell survival after uv irradiation. This effect in X-irradiated cells was limited to agents which uncouple oxidative phosphylation, and may be related to facilitated DNA repair.