Fixation of Potentially Lethal Radiation Damage in Chinese Hamster Cells by Anisotonic Solutions, Polyamines, and DMSO

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Abstract
The effect of anisotonic solutions, dimethyl sulfoxide (DMSO) and polyamines on the fixation of potentially lethal damage (PLD) was examined. Exposure to anisotonic solutions after irradiation resulted in large decreases in cell survival in a radiation dose-dependent manner. Maximum increase in survival due to repair of PLD in [Chinese hamster lung fibroblasts] V79 cells after a 1000-rad dose was about a factor of 4 while maximum decrease in survival due to fixation of damage was greater than 1000 times for some of the salt treatments tested. The fixation of PLD was greater and more rapid as the ion concentration was varied further from isotonicity. Irradiation at 0.degree. C resulted in more damage fixation by 0.05 or 1.5 M NaCl than irradiation at 37.degree. C. Fixation of PLD was also observed when cells were exposed to 1.0 or 2.0 M DMSO or 0.1 mM spermine or spermidine solutions. Fixation occurred in both exponentially growing cells and plateau-phase cells. A large amount of PLD which is normally not expressed can be converted to lethal damage by a variety of postirradiation treatments and the PLD repair capacity of the cell may be very large.