Induction of mucosal glutathione synthesis by arsenic

In the rat, oral administration of 1 mg/kg arsenic (as As2O3) binds rapidly to mucosal glutathione such that effective glutathione concentration is reduced. In response to the binding of arsenic to glutathione, de novo synthesis of glutathione occurs in the mucosal cell, resulting in twice the normal concentrations of glutathione within 3 h. This finding may explain acquired tolerance to arsenic, as well as the protective effect of arsenic against selenium toxicity.