Cellular glutathione as a determinant of sensitivity to mercuric chloride toxicity

Depletion of glutathione (GSH) by treatment of mice with buthionine sulfoximine (BSO), an effective inhibitor of gamma-glutamylcysteine synthetase, markedly enhanced (about 10-fold) the lethal and renal toxicity of mercuric chloride. The lethal toxicity of HgCl2 was prevented by administration of GSH monoester; this was observed in mice pretreated with BSO and given a low dose of HgCl2, and also in untreated mice that were given a much higher dose of HgCl2. In contrast, administration of GSH did not protect. Since administered GSH is not transported effectively into cells, whereas GSH monoester is transported and split intracellularly to GSH, the findings indicate that protection against HgCl2 requires intracellular GSH. The experimental approaches used here suggest that cellular GSH is a major determinant of sensitivity to HgCl2 toxicity, and also that administration of GSH esters may be useful for prevention of HgCl2 toxicity.