Paraquat increases superoxide dismutase activity and radiation resistance in two mouse lymphoma L5178Y cell strains of different radiosensitivities.
It is shown that paraquat treatment (1 h, 1 x 10(-5) mol/l) increases the activity of superoxide dismutase (SOD) in L5178Y (LY) R and S cells by about three times. When combined with X-irradiation, 0.5 h of treatment preceding irradiation increased the SOD activity two-fold and the alpha/beta ratio three-fold, as estimated from the X-ray survival curves. LY-S cells were more sensitive than LY-R cells to treatment with paraquat alone. These results indicate that SOD may be a radioprotective enzyme in LY strains and that LY-S cells are particularly sensitive to superoxide radicals as a result of a relatively low SOD activity. This explains their sensitivity to paraquat, which generates O2-, and to X-rays. The low SOD level may also explain the higher initial DNA damage in X-irradiated LY-S than LY-R cells.
Department of Radiobiology, Institute of Nuclear Chemistry and Technology, Warszawa, Poland.
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D000818:Animals; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D007700:Kinetics; D051379:Mice; D010269:Paraquat / Q000494:pharmacology* / Q000633:toxicity; D011836:Radiation Tolerance / Q000187:drug effects*; D013482:Superoxide Dismutase / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
D013482:Superoxide Dismutase; D010269:Paraquat