Lipid absorption in bile fistula rats. Lack of a requirement for biliary lecithin

The role of biliary or dietary phosphatidylcholine (lecithin) in the process of lipid absorption was studied in bile fistual rats. Jejunal lipid-reesterifying enzyme activities were determined in experimental rats given diet, bile salts and phosphatidylethanolamine and results compared to controls given diet alone. Lipid absorption was also studied in vivo with radioactive techniques. Two groups of bile tistula rats were used. Both received diet and bile salts. In addition, one group was given phosphatidylethanolamine and the other received lecithin. Enzyme activities were moderately but significantly reduced in bile tistula rats receiving phosphatidylethanolamine. This was associated with an abnormal phospholipid composition of the microsomal membrane. Despite the changes in mucosal enzyme activity, however, no abnormality of lipid absorption was noted in bile fistula rats that received phosphatidylethanalamine. Results in this group were similar to controls and to the other bile fistula group given lecithin. In all groups, significant amounts of lecithin were recovered from the lumen of the small bowel. It is concluded that if lecithin is required for lipid absorption, it does not have to be supplied to the small bowel via the diet or in bile.