Organ distribution and cellular uptake of methyl mercury in the rat as influenced by the intra- and extracellular glutathione concentration

Abstract

Intravenous administration of CH3HgCl (4 mumol/Kg) premixed with glutathione or cysteine (8 mumole/kg) to female rats caused a rapid uptake of mercury in the kidney and a depressed content in the liver and blood as compared to CH3HgCl given alone. GSH depletion in the tissues, produced by injection of diethylmaleate, DEM (3.9 mmole/kg) did not influence the kidney uptake of mercury from administered (CH3Hg+-GSH, whereas the uptake of injected CH3HgCl was depressed. Both GSH and cysteine (8 mumole/kg) promoted the biliary excretion of methyl mercury. In suspensions of rat erythrocytes and isolated hepatocytes, additions of GSH reduced the cellular uptake of CH3Hg+ from the medium, whereas this was increased in the hepatocytes by adding cysteine or methionine. Cysteine addition slightly reduced the uptake of CH3Hg+ in the erythrocytes. GSH-depletion as obtained by DEM pretreatment of the cells, reduced the Ch3Hg+ uptake into hepatocytes by 40%, in contrast to only a negligible effect on the erythrocytes. Our results support previous reports that a physiological CH3Hg+-GSH-complexation takes place intracellularly, at least in liver cells. Our results are furthermore consistent with the assumption that biliary excreted CH3Hg+-GSH, which can be reabsorbed, only to a limited extent is taken up by the liver, whereas this GSH-complexation and reabsorption is of importance for the Ch3Hg+-uptake in the kidneys.