[Cytogenetic effect of irradiation and subsequent cytosine arabinoside and hydroxyurea treatment on Chinese hamster cells in the G1 phase of the cell cycle].

A two-hour treatment of Chinese hamster cells at the G1 stage of the cell cycle with arabinoside cytosine combined with hydroxyurea after X-irradiation (50-300 cGy) produced a 2- to 4-fold increase in the frequency of chromosome aberrations. The mitotic selection method was used to synchronize the cells. The potentiating effect of the inhibitors, that was estimated by the yield of centric exchanges, decreased with increasing radiation dose. It is suggested that DNA repair processes determining a linear component of the dose-response curve are modified within the dose-range under study.