Effect of dose rate on cell killing and DNA strand break repair in CHO cells exposed to internal beta-rays from incorporated [3H]thymidine |
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| Authors: | E Dikomey |
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| Institution: | Institute of Biophysics and Radiobiology, University of Hamburg, Federal Republic of Germany. |
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| Abstract: | 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. |
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