Effect of Membrane Lipid Perturbers on the Temperature Dependence of Repair of Sublethal and Potentially Lethal Radiation Damage

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Abstract
The repair of sublethal radiation damage (SLD) in Chinese hamster (V79) cells was investigated as a function of temperature in the presence and absence of the membrane lipid perturbers, butylated hydroxytoluene (BHT) or adamantanone, which decrease the viscosity of the membrane lipids. Addition of 0·01 mM BHT to the cells significantly increased the amount of repair of SLD over controls from 0 to 25°C but not from 30 to 37°C. The amount of repair of SLD decreased as a function of temperature to about 20°C and remained relatively constant thereafter till about 2·5°C where it began to decrease again. The change in the amount of repair at approximately 20°C coincides with a membrane lipid phase transition, as seen by spin labelling, in these cells. The repair of potentially lethal damage (PLD) was not increased by BHT at the two temperatures investigated (5 and 20°C). In fact, additional PLD was expressed when cells were incubated post-irradiation at these temperatures. The results imply that at least a component of the SLD repair system is membrane associated and that the SLD and PLD repair systems are independent.