Chromium (VI)-induced DNA damage in chick embryo liver and blood cells in vivo

Uptake of chromium (VI) and subsequent induction of DNA damage was examined in liver and blood cells of 14-day chick embryos after injection of sodium dichromate onto the inner shell membrane. Maximal loss of chromium from the inner shell membrane and distribution of chromium in liver, lung and blood was observed 2 h after injection. DNA strand breaks, interstrand cross-links and DNA--protein cross-links were measured using the alkaline elution technique. In chick embryo liver, chromium (VI) induced DNA cross-links in the absence of strand breaks. Maximal DNA cross-linking was detected in the liver 8 h after injection. Little or no DNA damage remained in the liver 10-24 h after injection. In contrast, chromium (VI) induced DNA strand breaks in the absence of cross-links in chick embryo blood cells. Maximal DNA strand breakage was observed in blood cells 8 h after injection. High levels of DNA strand breaks were present in blood cells even 24 h after treatment. These intra-embryonic tissue differences in chromium (VI)-induced DNA damage may be a result of the differences in glutathione, cytochrome P-450, other pathways of chromium (VI) metabolism or chromatin organization which exist in liver and blood cells.