Background/Aims: The aim of this study was to investigate whether a carrier-mediated membrane transport for long chain fatty acid (LCFA) exists in the human intestinal mucosa. Methods: Biopsies obtained from the small intestine of patients, during routine endoscopies, were incubated for different periods in the presence of [3H]oleic acid complexed to albumin, and lipid fractions were separated and quantified. Biopsies were also incubated during 5 min in different oleic acid:albumin molar ratios. The effect of temperature on lipid transport was tested by incubating biopsies at 37 and 4°C. Results: Maximum [3H]oleic acid uptake occurred at 15 min. With increasing unbound oleic acid concentrations in the medium, LCFA uptake during 5 min of incubation revealed a typical saturation kinetics profile, and exhibiting apparent Km values of 3.43 ± 0.83 µM, and apparent Vmax values of 0.86 ± 0.07 nmol·min–1·mg–1. Within this period, nearly all intracellular fatty acid remained in the unesterified form. The system was also temperature-dependent, having shown a significant reduction of 78.03% in [3H]oleic acid uptake at 4°C, in 5 min of incubation. Conclusions: Our data confirm that LCFA uptake by human intestinal mucosa is likely to occur via a saturable carrier.

1.
Stremmel W, Berk PD: Hepatocellular influx of [14C]oleate reflects membrane transport rather than intracellular metabolism or binding. Proc Natl Acad Sci USA 1986;83:3086–3090.
2.
Stremmel WJ, Diede HE: Fatty acid uptake by human hepatoma cell lines represents a carrier-mediated uptake process. Biochim Biophys Acta 1989;1013:218–222.
3.
Abumrad NA, Perkins RC, Park JH, Park CR: Mechanism of long chain fatty acid permeation in the isolated adipocyte. J Biol Chem 1981;256:9183–9191.
4.
Abumrad NA, el-Maghrabi MR, Amri EZ, Lopez, E, Grimaldi PA: Cloning of a rat adipocyte membrane protein implicated in binding or transport of long-chain fatty acids that is induced during preadipocyte differentiation. Homology with human CD36. J Biol Chem 1993;268:17665–17668.
[PubMed]
5.
Degrella RF, Light RJ: Uptake and metabolism of fatty acids by dispersed adult rat heart myocytes. I. Kinetics of homologous fatty acids. J Biol Chem 1980;2550:9731–9738.
6.
Stremmel W, Pohl L, Ring A, Herrmann T: A new concept of cellular uptake and intracellular trafficking of long-chain fatty acids. Lipids 2001;36:981–989.
[PubMed]
7.
Chow SL, Hollander D: A dual, concentration-dependent absorption mechanism of linoleic acid by rat jejunum in vitro. J Lipid Res 1979;20:349–356.
8.
Schoeller C, Keelan M, Mulvey G, Stremmel W, Thomson AB: Oleic acid uptake into rat rabbit jejunal brush border membrane. Biochim Biophys Acta 1995;1236:51–64.
[PubMed]
9.
Stremmel W: Uptake of fatty acids by jejunal mucosal cells is mediated by a fatty acid binding membrane protein. J Clin Invest 1988;82:2001–2010.
[PubMed]
10.
Poirier H, Degrace P, Niot I, Bernard A, Besnard P: Localization and regulation of the putative membrane fatty acid transporter in the small intestine. Comparison with fatty acid-binding proteins. Eur J Biochem 1996;238:368–373.
[PubMed]
11.
Tranchant T, Besson P, Hoinard C, Delarue J, Antoine JM, Couet C, Gore J: Mechanisms and kinetics of α-linolenic acid uptake in Caco-2 clone TC7. Biochim Biophys Acta 1997;1345:151–161.
12.
Trotter PJ, Ho SY, Storch J: Fatty acid uptake by Caco-2 human intestinal cells. J Lipid Res 1996;37:336–346.
[PubMed]
13.
Lowry OH, Rosebrough NJ, Farr AL, Randall RJ: Protein measurement with the Folin phenol reagent. J Biol Chem 1951;193:265–275.
[PubMed]
14.
Bligh EG, Dyer WJ: A rapid method of total lipid extraction and purification. Can J Biochim Physiol 1959;37:911–917.
15.
Kvilekval K, Lin J, Cheng W, Abumrad N: Fatty acids as determinants of triglyceride and cholesteryl ester synthesis by isolated hepatocytes: Kinetics as a function of various fatty acids. J Lipid Res 1994;35:1786–1794.
16.
Chow SL, Hollander D: Arachidonic acid intestinal absorption: Mechanism of transport and influence of luminal factors on absorption in vitro. Lipids 1978;13:768–776.
17.
Chow SL, Hollander D: Linoleic acid absorption in the unanesthetized rat: Mechanism of transport and influence of luminal factors on absorption. Lipids 1979;14:378–385.
18.
Gore J, Hoinard C: Linolenic acid transport in hamster intestinal cells is carrier-mediated. J Nutr 1993;123:66–73.
19.
Rachmilewitz D, Sharon P, Eisenberg S: Lipoprotein synthesis and secretion by cultured human intestinal mucosa. Eur J Clin Invest 1980;10:125–131.
20.
Zakim D: Fatty acids enter cells by simple diffusion. Proc Soc Exp Biol Med 1996;212:5–14.
[PubMed]
You do not currently have access to this content.