The in vivo binding of chromium to whole chromatin, polynucleosomes, DNA, and cytoplasmic RNA-protein fraction from liver and kidney was examined after treatment of rats with sodium dichromate and chromium(III) chloride. Significant amounts of chromium were bound to DNA and the nonhistone proteins of chromatin and to cytoplasmic RNA-protein fraction. The binding of chromium to the nuclear and cytoplasmic nucleic acid fractions varied considerably, depending on the tissue and the oxidation state of the chromium administered. The level of chromium bound to whole chromatin was greater in the liver than in the kidney after treatment with either chromium compound. Chromium entered the liver and kidney tissues at a slower rate after chromium(III) treatment than after chromium(VI) treatment. At early times after chromium(VI) treatment, more chromium was bound to the liver and kidney chromatin and DNA than after chromium(III) treatment. A much smaller proportion of the chromium bound to chromatin was associated with the DNA after treatment with chromium(III) than after treatment with chromium(VI). However, 40 hr after injection, there was no significant difference in the level of chromium on the DNA from both the liver and kidney of chromium(VI)- and chromium(III)-treated animals. No DNA damage was detected in either liver or kidney nuclei after chromium(III) treatment, using the technique of alkaline elution. A possible correlation between chromium binding to chromatin and DNA damage is discussed.
This investigation was supported by Grant BC-320 from the American Cancer Society, by USPHS Grant CA34869 awarded by the National Cancer Institute, Department of Health and Human Services, by the donors of the Petroleum Research Fund, administered by the American Chemical Society, and by A. P. Sloan Research Fellowship.