Preferential Uptake of Dietary Fatty Acids in Adipose Tissue and Muscle in the Postprandial Period
- Alex S.T. Bickerton1,
- Rachel Roberts1,
- Barbara A. Fielding1,
- Leanne Hodson1,
- Ellen E. Blaak2,
- Anton J.M. Wagenmakers3,
- Marjorie Gilbert1,
- Fredrik Karpe1 and
- Keith N. Frayn1
- 1Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, U.K
- 2Nutrition and Toxicology Research Institute Maastricht, University of Maastricht, the Netherlands
- 3School of Sport and Exercise Sciences, University of Birmingham, Birmingham, U.K
- Address correspondence and reprint requests to Keith N. Frayn, PhD, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Old Road, Headington, Oxford, OX3 7LJ, U.K. E-mail: keith.frayn{at}oxlip.ox.ac.uk
Abstract
Despite consistent evidence that abnormalities of fatty acid delivery and storage underlie the metabolic defects of insulin resistance, physiological pathways by which fat is stored in adipose tissue and skeletal muscle are not clear. We used a combination of stable isotope labeling and arteriovenous difference measurements to elucidate pathways of postprandial fat deposition in adipose tissue and skeletal muscle in healthy humans. A test meal containing [U-13C]palmitate was combined with intravenous infusion of [2H2]palmitate to label plasma fatty acids and VLDL-triglyceride. Both dietary (chylomicron) and VLDL-triglyceride were cleared across adipose tissue and muscle, though with greater fractional extraction of the chylomicron-triglyceride. In adipose tissue there was significant uptake of plasma nonesterified fatty acids (NEFAs) in the postprandial but not the fasting state. However, this was minor in comparison with chylomicron-triglyceride fatty acids. We modeled the fate of fatty acids released by lipoprotein lipase (LPL). There was clear preferential uptake of these fatty acids compared with plasma NEFAs. In muscle, there was unexpected evidence for release of LPL-derived fatty acids into the plasma. With this integrative physiological approach, we have revealed hidden complexities in pathways of fatty acid uptake in adipose tissue and skeletal muscle.
Footnotes
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- Accepted October 10, 2006.
- Received June 16, 2006.
- DIABETES
