Pre-irradiation with low doses has no detectable effect on the repair of radiation-induced double strand breaks in DNA of Chinese hamster V79 cells

When cells are exposed to preliminary low doses of ionising radiation prior to much higher doses, the overall extent of cell damage is reduced by an effect known as the adaptive response. We have extended such studies to include measurements of double strand breaks (DSB) in the DNA of Chinese hamster V79 cells, but, surprisingly, pretreatment with low doses had no effect on the numbers of DSB. This contrast is discussed in terms of DNA repair mechanisms.