LIPIDS IN TOTAL PARENTERAL-NUTRITION SOLUTIONS DIFFERENTIALLY MODIFY LIPIDS IN PIGLET INTESTINAL BRUSH-BORDER AND MICROSOMAL-MEMBRANES

Background: Fats in the diet modify the lipid composition and function of the intestinal brush border membrane (BBM) as well as the enterocy te microsomal membrane (EMM). Methods: This study was undertaken in pi gs to establish the effect of 3 weeks of total parenteral nutrition (T PN) on the fatty acids in the major phospholipids, (phosphatidylcholin e [PC] and phosphatidylethenolamine [PE]) in the jejunal and ileal BBM and EMM. Results: In a comparison of 21-day-old milk-fed piglets and newborn animals, there were differences in the major fatty acids (palm itic, 16:0; stearic, 18:0; oleic, 18:1 omega 9, and linoleic acid, 18: 2 omega 6) in PC and PE in BBM and EMM. Age-matched (3-week-old) anima ls fed a lipid-free glucose-containing TPN solution had different memb rane fatty acids than did milk-fed piglets, or animals given a soybean oil-containing TPN solution for 21 days. Substituting fish oil or fis h oil plus soybean oil altered BBM and EMM fatty acids, compared with the soybean oil-based TPN solutions. These changes varied between the class of phospholipids (PC vs PE), between intestinal site (jejunum us ileum), and between the type of membrane (BBM vs EMM). Conclusions: T he jejunum and ileum have distinctive control mechanisms for varying t heir membrane lipids in response to TPN. There is some postmicrosomal modification of lipids between the EMM and BBM. It remains to be estab lished whether the Lipid content of the membranes of other organs, and therefore their function, is modified by the lipid composition of par enterally infused lipids.