Low-dose-rate irradiation of rat embryo cells containing the Ha-ras oncogene.

Rat embryo cells and derived transfectants containing the Ha-ras oncogenes were irradiated with 60Co gamma rays at dose rates of 0.72, 0.066, 0.035, and 0.018 Gy/min. The measured dose response of cell survival shows that the oncogene-containing cells exhibit higher survival levels at all doses than the parental cells at every dose rate. The response of the cells containing the ras oncogene also became dose-rate independent at a higher dose rate, perhaps indicative of a greater repair capability relative to that of the primary cells.