Chromium(VI)-induced DNA lesions and chromium distribution in rat kidney, liver, and lung

DNA lesions were detected in rat organ nuclei following an i.p. injection of sodium dichromate. Kidney, liver, and lung nuclei were examined for DNA interstrand cross-links, strand breaks, and DNA-protein cross-links using the alkaline elution technique. The time course for formation of cross-links in kidney nuclei revealed the presence of DNA interstrand and DNA-protein cross-links 1 hr after injection of sodium dichromate. By 40 hr in kidney, DNA interstrand cross-links had been repaired, but DNA-protein cross-links persisted. In liver nuclei, the time course for formation of cross-links after injection of dichromate showed a maximum in DNA-protein cross-linking at 4 hr and a maximum in DNA interstrand cross-linking at 2 hr. By 36 hr, in the liver, both types of lesions had been repaired. In lung nuclei, both DNA interstrand and DNA-protein cross-links were observed 1 hr after dichromate injection; however, by 36 hr, only DNA-protein cross-links persisted. No DNA lesions were detectable in kidney 1 hr after an i.p. injection of chromium(III) chloride. Chromium distribution in rat kidney, liver, and lung was measured and is discussed with respect to the observed DNA lesions. The lung and kidney may be more sensitive than liver to chromium-induced DNA damage, an observation which correlates with the reported toxicity and carcinogenicity data for chromium(VI) in both animals and humans.