In vivo reduction of arsenate in mice and rabbits.

In vivo reduction of AsV, has been studied in mice and rabbits by determination of arsenic metabolites in plasma and urine after administration of [74As]arsenate. The amount of AsIII in bladder urine of mice 1 hr after administration (0.04 or 0.4 mg As/kg body wt) corresponded to 0.4-2.9% of the dose. AsIII was also detected in plasma 1 hr after administration. In rabbits, catheterized in the bladder for continuous collection of urine, about 10% of the administered arsenate (0.04 mg As/kg body wt) was reduced and excreted in form of AsIII during 4 hr after administration, corresponding to about 20% of the total arsenic excreted. Arsenic excreted during the first hour was mainly in form of unmetabolized AsV and some AsIII. Thereafter the excretion of both AsIII and dimethylarsinic acid increased. The results indicated that AsV has to be reduced to AsIII before being methylated.