Effects of different growth conditions on survival after irradiation in hypoxia of human cells (NHIK 3025) in vitro.

Cell cycle kinetics and radiation response under hypoxic conditions were analyzed with human cells of the line NHIK 3025. The cells were either kept in continuous exponential growth by frequent reculturing, or went through log and plateau phase for each passage (recultured weekly). The cell cycle time for weekly recultured populations in early log phase was shorter than for cells in continous exponential growth. Cells in continuous exponential growth were more sensitive to radiation than cells in log phase. The difference in sensitivity was not due to partial synchrony of weekly recultured populations.