Reduced Incorporation of Fatty Acids Into Triacylglycerol in Myotubes From Obese Individuals With Type 2 Diabetes

  1. Patrick Schrauwen1
  1. 1Department of Human Biology, NUTRIM—School for Nutrition, Toxicology and Metabolism, Departments of Human Biology, Maastricht University Medical Center, Maastricht, the Netherlands
  2. 2Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL
  3. 3Department of Human Movement Sciences, NUTRIM—School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands
  4. 4Institute of Molecular Biosciences, University of Graz, Graz, Austria
  1. Corresponding author: Patrick Schrauwen, p.schrauwen{at}maastrichtuniversity.nl.
  1. L.M.S., M.B., M.K.C.H., and P.S. contributed equally to this work.

Abstract

Altered skeletal muscle lipid metabolism is a hallmark feature of type 2 diabetes (T2D). We investigated muscle lipid turnover in T2D versus BMI-matched control subjects (controls) and examined whether putative in vivo differences would be preserved in the myotubes. Male obese T2D individuals (n = 6) and BMI-matched controls (n = 6) underwent a hyperinsulinemic-euglycemic clamp, VO2max test, dual-energy X-ray absorptiometry scan, underwater weighing, and muscle biopsy of the vastus lateralis. 14C-palmitate and 14C-oleate oxidation rates and incorporation into lipids were measured in muscle tissue as well as in primary myotubes. Palmitate oxidation (controls: 0.99 ± 0.17 nmol/mg protein; T2D: 0.53 ± 0.07 nmol/mg protein; P = 0.03) and incorporation of fatty acids (FAs) into triacylglycerol (TAG) (controls: 0.45 ± 0.13 nmol/mg protein; T2D: 0.11 ± 0.02 nmol/mg protein; P = 0.047) were significantly reduced in muscle homogenates of T2D. These reductions were not retained for palmitate oxidation in primary myotubes (P = 0.38); however, incorporation of FAs into TAG was lower in T2D (P = 0.03 for oleate and P = 0.11 for palmitate), with a strong correlation of TAG incorporation between muscle tissue and primary myotubes (r = 0.848, P = 0.008). The data indicate that the ability to incorporate FAs into TAG is an intrinsic feature of human muscle cells that is reduced in individuals with T2D.

Footnotes

  • Received July 19, 2013.
  • Accepted January 26, 2014.

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  1. Diabetes vol. 63 no. 5 1583-1593
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