Modification of the Radiosensitivity of Hamster Cells in vitro

THE radiosensitivity of hamster cells in vitro was increased by incubation with 5-bromodeoxycytidine prior to X-irradiation. The change in radiosensitivity was determined by a modification of the Puck technique 6 in which the survival of clones as a function of X-ray dose was compared with the survival of clones derived from cells incubated for varying periods prior to irradiation in medium containing 5-bromodeoxycytidine. The details of similar experiments in which 5-bromodeoxyuridine and 5-fluorouracil were tested are described elsewhere 1,2 .