Effects of potassium dichromate on ATP content of mammalian cells cultured in vitro.

In order to elucidate the mechanism of the cytotoxic activity of hexavalent chromium (Cr(VI)), the alterations of intracellular ATP levels induced by potassium dichromate in cultured hamster fibroblasts (BHK line) have been studied. Two kinds of treatment procedures were adopted: (1) BHK cell suspensions were exposed to 0.05--1.00 mM K2Cr2O7 in Hanks' balanced salt solution (BSS) for up to 180 min and ATP concentrations were determined immediately after the exposure to Cr(VI). A decrease of ATP content was observed with 0.25--12.00 mM K2Cr2O7 but only in the case of the highest dose was it related in a linear fashion to the duration of the treatment. (2) Cells were preincubated in BSS for 30 min with 0.05--1.00 mM dichromate. They were then reincubated in Eagle's minimal essential medium (MEM) for up to 180 min and ATP was measured at different time points. Immediately after the exposure to chromium all the treated cultures showed a depletion of ATP content. However while the cells treated with 0.25--0.25 mM dichromate rapidly resumed ATP levels very similar to that of the control, no recovery was detected in cells treated with 0.50 and 1.0 mM K2Cr2O7, even after 180 min. The observed effects have been attributed to the oxidizing activity of Cr(VI), which subtracts electrons from electron donors involved in metabolic pathways producing ATP, and to the ability of Cr(III), deriving from Cr(VI) reduction, to form stable coordination complexes with ATP precursors and enzymes involved in ATP synthesis.