COMPARISON OF MUTAGENICITY AND INDUCTION OF SISTER CHROMATID EXCHANGE IN CHINESE-HAMSTER CELLS EXPOSED TO HEMATOPORPHYRIN DERIVATIVE PHOTORADIATION, IONIZING-RADIATION, OR ULTRAVIOLET-RADIATION

Abstract

Cell culture studies were performed to compare the mutagenic potential and the induction of sister chromatid exchanges for hematoporphyrin derivative photoradiation, ionizing radiation and UV radiation. The mutation frequency in Chinese hamster ovary cells at the hypoxanthine-guanine phosphoribosyltransferase locus was measured using resistance to 6-thioguanine. Phenotypic expression time prior to mutation selection was also examined. Treatment with either X-rays or UV was effective in producing mutants resistant to 6-thioguanine, but treatment with hematoporphyrin derivative photoradiation (at comparable toxicity levels) did not induce any mutagenic activity above background levels. The hematoporphyrin derivative incubation and photosensitization conditions used did induce sister chromatid exchanges at frequencies comparable to those induced by X-rays but at lower frequencies than for UV treatments.