Effect of dose rate on cell killing and DNA strand break repair in CHO cells exposed to internal beta-rays from incorporated [3H]thymidine.
Survival as well as repair of DNA strand breaks were studied in CHO cells after exposure to internal beta-rays from incorporated [3H]thymidine at 4 degrees C (equivalent to an exposure at 'infinitely high' dose rate) and at 37 degrees C (low dose rate). DNA strand breaks were determined by the alkaline unwinding technique. In cells exposed at 4 degrees C cell killing was five times higher (Do = 250 decays per cell) than in cells exposed at 37 degrees C (Do = 1280 decays per cell). Strand breaks induced by 3H decay at 37 degrees C were repaired with the same kinetics as those generated at 4 degrees C. Therefore the different degrees of cell killing at 4 degrees C and 37 degrees C cannot be attributed to a difference in the repair kinetics for DNA strand breaks.
Dikomey
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Institute of Biophysics and Radiobiology, University of Hamburg, Federal Republic of Germany.
D000818:Animals; D001610:Beta Particles; D002470:Cell Survival / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D011829:Radiation Dosage; D013936:Thymidine; D014316:Tritium
D014316:Tritium; D004247:DNA; D013936:Thymidine