Toxic effect of chromium on cellular metabolism.

The cytotoxic action of Cr(VI) in intact mammalian cells is strictly related to its carrier-mediated transport across the plasma membrane and its reduction to Cr(III) inside the cell. A marked decrease in the ratio of reduced/oxidized glutathione in rat thymocytes treated with dichromate indicates an involvement of glutathione in the reduction of Cr(VI) to Cr(III) in these cells. Intracellular chromium is shown to interfere with specific steps of cellular energy metabolism in that it produces severe unbalance of purine ribonucleotide pools in hamster fibroblast cultures and inhibition of mitochondrial oxygen consumption in rat thymocytes at micromolar concentrations. To what extent the effects caused by Cr(VI) are directly related to the reduction process or to the subsequent binding of Cr(III), and possibly of Cr(V), to biological molecules playing a critical role in cell physiology, remains to be elucidated.