Arsenic metabolism in hyperbilirubinemic rats: Distribution and excretion in relation to transformation

Publisher Summary Diverse chemical species of arsenic (As) are taken up by humans through dietary foods and water. The most important chemical species from the viewpoint of the toxicity and exposure to humans are arsenite (iAsIII) and arsenate (iAsV). Because the inorganic As absorbed in the body is excreted in the urine mostly in the form of dimethylated arsenic (DMA), the toxicity of As must be caused by one of the metabolites during its transformation. Arsenite (As) absorbed by the body is believed to be transferred to the liver, and then it is transformed by consecutive methylation and reduction reactions to DMA. iAsIII is oxidatively methylated to monomethylarsonic acid (MMAV) and then reduced to monomethylarsonous acid (MMAIII) for further oxidative methylation to dimethylarsinic acid (DMAV). In rats, DMAV is reduced efficiently to dimethylarsinous acid (DMAIII) and then excreted into the bloodstream, where DMAIII is sequestered selectively by erythrocytes, resulting in the selective accumulation of As in erythrocytes in rats.