Repair of potentially lethal damage in Chinese hamster cells after X and alpha irradiation.

Recovery from potentially lethal damage (PLD) of cultured Chinese hamster cells (line CHO) after exposure to X rays and to α particles was investigated using both exponentially growing and plateau-phase cells (nutritionally induced stationary phase). The results indicated that there was no recovery from PLD after exposure to α particles from plutonium. Experiments were also conducted to determine if recovery phenomena were dependent on cell concentration. Recovery from PLD after X-ray exposure was not dependent on cell concentration. Cell-to-cell contact also does not seem to be an important factor in PLD recovery. The recovery curve shape after exposure to X rays, both for exponentially growing and plateau-phase CHO cells, remained identical; however, the magnitude of repair by plateau-phase cells was higher than by exponentially growing cells, indicating that cells in G1 may be primarily involved in PLD recovery.