Dietary fat selectively alters transport properties of rat jejunum.

The influence of dietary fatty acid composition on intestinal active and passive transport function, brush border membrane com- position, and morphology was examined in rats.Animals fed a semisynthetic diet high in saturated fatty acids demonstrated enhanced in vitro jejunal uptake ofdecanoic, dodecanoic, palmitic, stearic, and linoleic acid, as well as cholesterol and chenode- oxycholic and taurochenodeoxycholic acid, as compared with uptake in animals fed a semisynthetic diet high in polyunsatu- rated fatty acids but equivalent in total content of fat and other nutrients, or as compared with Purina chow.Feeding the satu- rated fatty acid diet was also associated with reduced jejunal uptake of a range of concentrations of glucose, enhanced ileal uptake of leucine, unchanged uptake of galactose, and lower up- take ofdecanol.The semisynthetic diets did not alter brush border membrane protein, sucrase or alkaline phosphatase activities, cholesterol, or total phospholipids, although the percentage of jejunal amine phospholipids was higher than in rats fed chow.The morphologic differences between the jejunum and ileum were abolished in animals fed the high polyunsaturated fatty acid diet; in rats fed the high saturated fatty acid diet, there was reduced mean ileal villus height, width, thickness, surface area, cell size, and villus density, as well as reduced mucosal surface area.The changes in jejunal transport were not correlated with the alter- ations in morphology, unstirred layer resistance, food intake, or body weight gain.It is proposed that small changes in the per- centage of total dietary lipids composed of essential and non- essential fatty acids (without concurrent alterations in dietary total fat, carbohydrate, or protein) influence active and passive intestinal transport processes in the rat.Probe and marker compounds.[3Hlinulin (-5,000 mol wt) was used as supplied by the manufacturer (New England Nuclear, Boston, MA) to measure the adherent mucosal fluid volume.The '4C-labeled probes included cholic acid (CA), glycocholic acid (GCA), chenodeoxycholic acid (CDCA), taurochenodeoxycholic acid (TCDCA), decanol, D-and L-glucose, D-galactose, L-leucine, octanoic acid (fatty acid [FA] 8:0), dec- anoic acid (FA 10:0), dodecanoic acid (FA 12:0), myristic acid (FA 14: 0), palmitic acid (FA 16:0), stearic acid (FA 18:0), oleic acid (FA 18: 1), linoleic acid (FA 18:2), linolenic acid (FA 18:3), and cholesterol.Un- labeled and '4C-labeled probes were supplied by Sigma Chemical Co. 1.