RESUMO
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 [(3)H]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 degrees C. RESULTS: Maximum [(3)H]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 K(m) values of 3.43 +/- 0.83 microM, and apparent V(max) values of 0.86 +/- 0.07 nmol x min(-1) x 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 [(3)H]oleic acid uptake at 4 degrees 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.
