BILIARY-EXCRETION OF SILVER IN THE RAT, RABBIT, AND DOG

The fecal elimination of silver is more important than urinary elimination. Within 4 days after iv administration of silver to the rat (0.1 mg/kg), 70% is excreted into the feces and less than 1% into the urine. The disappearance of 110Ag from the plasma and its excretion into the bile were measured for 2 hr after the iv administration of 0.01, 0.03, 0.1, and 0.3 mg/kg of silver to rats. The concentration of silver in the bile was 16-20 times higher than that of the plasma. With the two lower doses of silver used, the overall plasma-to-bile gradient was due almost equally to the plasma-to-liver gradient and the liver-to-bile gradient and with the two higher doses of silver the liver-to-bile gradient became more important. Marked species variation in the biliary excretion of silver was observed. Rabbits excreted silver at a rate about 1 10, and dogs excreted silver at a rate about 1 100 of that observed in the rat. These results suggest that while species variation exist, biliary excretion is an important route for the elimination of silver. © 1979.