title: Lipoprotein lipase activity does not predict very low-density lipoprotein-triglyceride fatty acid oxidation during exercise.
abstract: Exercise lowers plasma triglyceride levels, but the physiological mechanisms remain not fully elucidated. Lipoprotein lipase (LPL) is a key enzyme in facilitating fatty acid uptake from lipoproteins. As exercise increases the efficiency of very low-density lipoprotein-triglyceride (VLDL-TG) oxidation, we hypothesized that muscle LPL activity would be a rate-limiting step and predict VLDL-TG Fatty acids oxidation during exercise. Sixteen healthy, lean subjects (eight men and eight women) were examined before and during an acute exercise bout (90 minutes at 50% of VO2-max). Heparin-releasable LPL activity was measured in muscle and adipose tissue biopsies. Breath14CO2was measured after a primed-constant infusion of ex vivo labeled [14C]-triolein VLDL-TG. Fractional VLDL-TG storage was measured in adipose tissue biopsies. Exercise did not affect muscle LPL activity (P=.30). No association was observed between muscle LPL activity and VLDL-TG oxidation, neither in the basal state (P=.17) nor during exercise (P=.83). Exercise did not affect upper body or lower body adipose tissue LPL activity (both P=.92). The basal adipose tissue fractional VLDL-TG storage (abdominal.13%±9%; femoral 17%±10% (P=.18)) was not associated with upper body (P=.56) or lower body (P=.44) subcutaneous adipose tissue LPL activity. Muscle LPL activity does not predict VLDL-TG oxidation during rest or exercise. In addition, adipose tissue LPL activity was not associated with VLDL-TG storage during rest. This suggests that LPL activity is present in excess of what is required to facilitate lipid uptake for oxidation during both rest and exercise.
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.|The Danish Diabetes Academy, Odense, Denmark.
authors.forename: E
authors.identifier: http://orcid.org/0000-0001-8041-6994
authors.initials: E
authors.lastname: Søndergaard
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: I R
authors.initials: IR
authors.lastname: Andersen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: L P
authors.initials: LP
authors.lastname: Sørensen
authors.affiliation: Department of Nuclear Medicine and PET center, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: L C
authors.initials: LC
authors.lastname: Gormsen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D008079:Lipoproteins, VLDL; D014280:Triglycerides; C030106:very low density lipoprotein triglyceride; D008071:Lipoprotein Lipase
keywords: exercise; lipoprotein lipase; triglyceride; very low-density lipoprotein