Acute effects of a superoxide radical-generating system on DNA double-strand stability in Chinese hamster ovary cells. Determination by a modified fluorometric procedure.

The rate of oxyradical generation by a xanthine oxidase-xanthine system to acutely cause DNA strand breakage in Chinese hamster ovary cells was studied in a phosphate-buffered saline system. DNA strand breakage, measured by a fluorometric procedure, was found to increase curvilinearly as a function of oxyradical generation. Results of studying the ability of 5 mM mannitol, 10 mM dimethylthiourea, 300 micrograms superoxide dismutase/ml, or 1 mg catalase/ml to interfere with DNA damage at a high rate of oxyradical production best supported a hydrogen peroxide-promoted mechanism for DNA breakage.