Uptake of chromate by rat thymocytes and role of glutathione in its cytoplasmic reduction

Abstract

1. Chromate is taken up by rat thymocytes over a wide range of extracellular chromate concentrations (0˙074 ± 5˙0 mM).

2. Chromate uptake followed Michaelis-Menten kinetics and was inhibited by 4-acetamido-4′-isothiocyano-stilbene-2,2′-disulphonic acid, suggesting that the anion carrier was responsible for the uptake by rat thymocytes.

3. The decrease in chromate uptake by the thiol(SH)-blocking agent diethyl maleate, the increased chromate uptake caused by the thiol-protecting agent dithiothreitol, and the reduction of glutathione/glutathione disulphide ratio indicated that the maintenance of the integrity of SH-groups greatly influenced the uptake and reduction of Cr(VI), and that glutathione may be responsible for the intracellular reduction of Cr(VI) to Cr(III).