MODIFICATION OF RADIATION RESPONSE IN MAMMALIAN CELLS: THE REPAIR AND FIXATION OF X-RAY-INDUCED POTENTIALLY LETHAL DAMAGE.

The effects of anisotonic salt treatments, polyamines, dimethyl sulfoxide (DMSO), 5 prime -bromodeoxyuridine (BrdUrd) and hyperthermia on the repair and fixation of X-ray-induced radiation damage were examined in V79 Chinese hamster lung fibroblasts, Chinese hamster ovary cells, normal and ataxia telangiectasis (AT) human cells. Significant repair of potentially lethal damage (PLD) was observed when cells were held in Earle's balanced salt solutions, or in plateau phase, following exposure to X-radiation; a much greater recovery was observed when cells were incubated at 37 degree C between irradiation and subsequent exposure to anisotonic salts. Cells exposed to 1 or 2 mol/L DMSO or 10** minus **5 mol/L BrdUrd exhibited PLD repair patterns comparable to control cells. Contrary to the results of others, human AT homozygotes, like normal human cells, did sustain radiation damage that could be fixed or repaired by anisotonic salt treatment.