Dose-Rate Effects in Synchronous Mammalian Cells in Culture

Abstract

The life cycle and survival of synchronized HeLa and Chinese hamster cells were examined during continuous irradiation at dose rates of 38 or 90 rads per hour. The results indicate that over a given range of dose rates, life-cycle-related factors can play a significant role in what is commonly referred to as the dose-rate effect. Dose rates of 38 rads per hour for HeLa cells, and 90 rads per hour for V79 Chinese hamster cells essentially prevented cell division. Continuous irradiation had no effect on the progress of cells through G1 or S, but produced a G2 delay and prevented cell division. If the continuous irradiation was started just before mitosis, cell division was also prevented. Continuous irradiation at 38 rads per hour had no measurable effect on the life cycle or division of V79 cells during three successive generations.