DNA damage and repair in CHO cells following hematoporphyrin photoradiation.

The induction and repair of alkali labile lesions and single strand breaks in DNA of CHO cells following HpD photoradiation of X-irradiation has been examined. For treatments producing equal survival levels, the amount of DNA damage was less for HpD-photoradiated cells compared to X-irradiated cells. Both the time scale and the magnitude of repair of the DNA damage were the same for the 2 modalities, with the majority of repair occurring during the first 15 min of incubation and repair being essentially complete by 30 min.