Abstract
Anisotonic treatment of V79 cells after irradiation resulted in extensive fixation of potentially lethal damage (PLD). Fixation of PLD occurred more rapidly when treated with 1.5 mol l-1 NaCl than with 0.05 mol l-1 NaCl. These effects were further enhanced when cells were held at 0 degree C instead of 37 degrees C during irradiation. When the X-ray (10.0 Gy) and salt treatments were separated by incubation at 37 degrees C, survival increased rapidly by a factor of 2000, while repair of PLD in cells held in a plateau phase after X-rays (10.0 Gy) caused survival to increase four-fold. The data indicate that these mammalian cells sustain and repair a much larger amount of PLD than is measured by the conventional method of holding cells in a non-progressing state after irradiation. Radiation sensitivity in cells was modified by BrdUrd incorporation into cellular DNA or exposure to DMSO during irradiation. For these cells, fixation of damage by post-irradiation anisotonic treatment proceeded at the same rate for BrdUrd-treated cells, and at a diminished rate for DMSO-treated cells, compared with cells irradiated in the absence of these compounds. In C3H-10T 1/2 cells, post-irradiation anisotonic treatment (with 0.05 or 1.5 mol l-1 NaCl) also resulted in fixation of PLD and a rapid recovery when the X-ray and salt treatments were separated by incubation at 37 degrees C. Treatment with 0.05 or 1.5 mol l-1 NaCl solutions immediately after irradiation also resulted in elevated transformation frequencies, which increased with exposure time to anisotonic solutions.(ABSTRACT TRUNCATED AT 250 WORDS)
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