Effect of uncouplers on radiosensitivity and mutagenicity in x-irradiated mammalian cells.

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Abstract
The number of X-irradiated mammalian [rat hepatoma C4] cells surviving is markedly increased when the cells are incubated with an uncoupler of oxidative phosphorylation [m-chlorocarbonyl cyanide phenylhydrazone or carbonyl cyanide p-trifluoromethoxyphenylhydrazone] prior to or immediately after irradiation. This increase is greater in plateau-phase cells than in exponentially growing cells. The increase in survival is related to the potency of the uncouplers, which do not modify the effective X-ray dose. The influence of uncouplers on survival is related to an increase of repair and semiconservative DNA synthesis. The mutation frequency (8-azaguanine-resistant mutants) is significantly higher in irradiated cells treated with uncouplers than in untreated cells. The existence of an error-prone repair process in mammalian cells is suggested.