Stimulation of postirradiation DNA synthesis in ultraviolet irradiated HeLa cells by fluorodeoxyuridine.

The influence of precultivation with fluorodeoxyuridine (FdUrd) on the rate of overall DNA synthesis in ultraviolet (UV) irradiated HeLa cells has been studied. HeLa cells were pretreated either for 24 h with FdUrd, or for 6 h with FdUrd + 18 h in FdUrD-free medium before UV irradiation (10 Jm-2). Both pretreatments stimulated the rate of DNA synthesis not only in unirradiated but also in UV irradiated cells. It is concluded that precultivation of HeLa cells with FdUrd increased the UV resistance of DNA synthesis in comparison with untreated cells.