INORGANIC PENTAVALENT ARSENIC METHYLATION BY RATS - EFFECT OF CONCENTRATION AND DICHROMATE

The effect of the administered arsenic (As) dose and the dichromate io n (Cr) on the methylation process of arsenic was studied in rats expos ed to arsenate to elucidate the biotransformation of As. After oral ad ministration of different As (V) and Cr (VI) concentrations, the diffe rent As metabolites (inorganic, methylarsonic acid [MMA] and dimethyla rsinic acid [DMA]) were separated by cation-exchange chromatography an d measured by atomic absorption spectrophotometry. Administration of h igh doses of As produced enzymatic saturation and non-enzymatic deplet ion, with decreases in DMA levels. The presence of the dichromate ion supported arsenate methylation as it favored reduction of As (V) to As (III), but Cr (VI) produced a significant decrease in the total As ex creted.