A SURGICAL MODEL FOR DETERMINATION OF TRUE ABSORPTION AND BILIARY-EXCRETION OF MANGANESE IN CONSCIOUS SWINE FED COMMERCIAL DIETS

Some trace elements, such as Mn, Cu and Zn, are absorbed and quickly r esecreted into the gut through the bile. When this occurs, the unabsor bed nutrient and the absorbed and resecreted nutrient may mix in the g ut, preventing quantitative calculation of either. We have developed a surgical model that prevents this complication. Rigs (20-40 kg) were fitted with cannulas in the bile duct, lumen of the duodenum, portal v ein, ileocolic vein and jugular vein. After recovery for 6-8 d, pigs w ere given an oral dose of 9.25 mBq of Mn-54. The flow rate of blood pa st the portal vein was determined by infusion of P-amino hippuric acid into the ileocolic vein. Absorption was quantified by multiplying the concentration of Mn-54 in the portal blood by the flow rate. Biliary excretion was determined by quantitative collection of bile, and previ ously collected bile was reinfused into the gut lumen. Urine and feces were also,quantitatively collected. A postoperative time of 6-8 d was sufficient for pigs to recover from the effects of surgery and anesth esia, as assessed by several measures of metabolic function and food a nd water intake. True absorption was calculated to be 0.5%. Mn-54 in t he urine and bile began to increase after 4 d. When the pigs were kill ed after 12 d, only 0.5% of the Mn-54 remained in the carcass. Results of this study show that pigs surgically modified by the described pro cedure can recover fully and can serve as a model to study intestinal absorption and biliary excretion of nutrients. Furthermore, initial st udies using Mn-54 showed that the model is applicable to studying Mn m etabolism and suggest the need for a more detailed study of Mn absorpt ion and biliary excretion.