IN-VIVO EFFECTS OF CHROMIUM

The production of reactive oxygen species on addition of hexavalent ch romium (potassium dichromate, K2Cr2O7) to lung cells in culture was st udied using flow cytometer analysis. A Coulter Epics Profile II flow c ytometer was used to detect the formation of reactive oxygen species a fter K2Cr2O7 was added to A549 cells grown to confluence. The cells we re loaded with the dye, 2',7'-dichlorofluorescein diacetate, after whi ch cellular esterases removed the acetate groups and the dye was trapp ed intracellularly. Reactive oxygen species oxidized the dye, with res ultant fluorescence. Increased doses of Cr(VI) caused increasing fluor escence (10-fold higher than background at 200 mu M). Addition of Cr(I II) compounds, as the picolinate or chloride, caused no increased fluo rescence. Electron paramagnetic resonance (EPR) spectroscopic studies indicated that three (as yet unidentified) spectral ''signals'' of the free radical type were formed on addition of 20, 50, 100, and 200 mu M Cr(VI) to the A549 cells in suspension. Two other EPR ''signals'' wi th the characteristics of Cr(V) entities were seen at field values low er than the standard free radical value. Liver microsomes from male Sp rague-Dawley rats treated intraperitoneally with K2Cr2O7 (130 mu mole/ kg every 48 hr for six treatments) had decreased activity of cytochrom es P4503A1 and/or 3A2, acid 2C11. Hepatic microsomes from treated fema le Sprague-Dawley rats, in contrast, had increased activities of these isozymes. Lung microsomes from male Sprague-Dawley rats had increased activity of P4502C11.