Summary
HeLa cells in suspension were aerated with either oxygen or nitrogen while being irradiated with varying doses of 280 kVp x-rays. The cells were examined during the first mitosis after irradiation for types and frequencies of chromosome aberrations. Analysis of the single-hit and multi-hit chromosome aberrations resulted in oxygen-enhancement ratios of 1·32 and 2·93, respectively. Analysis of the total cytogenetic damage resulted in the following dose-response relationships: The oxygen-enhancement ratio based on these relationships was 1·81. These studies indicated that HeLa cell chromosomes have a similar radiosensitivity, but a higher spontaneous aberration frequency than that reported for normal mammalian cells.