Metabolism and renal handling of sodium arsenate in dogs

Renal handling of sodium arsenate was studied in 5 dogs. Using a low dose (0.73 mg/kg of body weight) of sodium arsenate given IV, variable arsenite concentrations were detected in plasma and urine. Using a medium dose (7.33 mg/kg), the renal tubule cells were determined to be the probable sites of reabsorption of arsenate, reduction of arsenate to arsenite, and secretion or diffusion of the latter into urine. However, using a high dose (14.66 mg/kg), despite a similar pattern of reduction of arsenate to arsenite, marked reabsorption of arsenite into plasma took place instead of secretion or diffusion into urine. Because of reabsorption, the amount of arsenite in plasma (18.4 +/- 3.5% of the total As) was about 3 times higher than that measured during the medium dose experiment (6.0 +/- 1.0%). During the clearance experiments which lasted 110 minutes, only 40% to 45% of the arsenate infused was excreted in urine, and a minimal amount of dimethylarsinic acid (DMAA) was detected. In contrast, by the next day, DMAA was the major metabolite excreted in urine. This excretion of As as DMAA was partly due to delayed excretion of 55% to 60% As that was stored in the body and was subsequently metabolized.