BILIARY-EXCRETION OF (51)CHROMIUM IN BILE-DUCT CANNULATED RATS

(51)Chromium excretion was studied in adult female Sprague Dawley rats following bile-duct cannulation. The cannulation technique allowed th e separation of bile from pancreatic secretions while enterohepatic ci rculation remained intact. Three days post-surgery, animals were depri ved of food overnight and intubated with a 1 ml solution of aspirin (2 0 mg/kg body weight) in 20% ethanol or 1 ml of 20% ethanol as a contro l. Intubation was followed immediately by an oral dose of 25 mu Ci of (CrCl3)-Cr-51 (0.18 mu g of chromium) by micropipette. Weighed samples of bile and blood were collected at 0, 15 and 30 minutes, and 1, 2 an d 4 hours after dosing. Six days post-surgery, the same bile-duct cann ulated rats were dosed with either aspirin in 20% ethanol or 20% ethan ol alone in a crossover design. Aspirin increased Cr-51 in blood compa red to control but did not affect the concentration of Cr-51 in bile s ignificantly. Concentrations of Cr-51 in bile were lower than in blood at all time periods. While bile appears to be a major avenue for the elimination of manganese and copper, our data indicate that the biliar y excretion of chromium during the first 4 hours after dosing is minim al and that biliary excretion is not an important homeostatic mechanis m for chromium.