title: Kinetics and utilization of lipid sources during acute exercise and acipimox.
abstract: Overweight is associated with abnormalities of lipid metabolism, many of which are reversed by exercise. We investigated the impact of experimental antilipolysis and acute exercise on lipid kinetics and oxidation from VLDL-TG, plasma FFA, and "residual lipids" in overweight men (n = 8) using VLDL-TG and palmitate tracers in combination with muscle biopsies in a randomized, placebo-controlled design. Participants received placebo or acipimox on each study day (4 h of rest, 90 min of exercise at 50% V(O(2 max))). Exercise suppressed VLDL-TG secretion significantly during placebo but not acipimox (placebo-rest: 64.2 ± 9.4; placebo-exercise: 48.3 ± 8.0; acipimox-rest: 55.2 ± 13.4; acipimox-exercise: 52.0 ± 10.9). Resting oxidation of VLDL-TG FA and FFA was significantly reduced during acipimox compared with placebo, whereas "residual lipid oxidation" increased significantly [VLDL-TG oxidation (placebo: 18 ± 3 kcal/h; acipimox: 11 ± 2 kcal/h), FFA oxidation (placebo: 14 ± 2 kcal/h; acipimox: 4 ± 0.5 kcal/h), and residual lipid oxidation (placebo: 3 ± 5 kcal/h; acipimox: 14 ± 5 kcal/h)]. Additionally, during exercise on both placebo and acipimox, oxidation of VLDL-TG and FFA increased, but the relative contribution to total lipid oxidation diminished, except for FFA, which remained unchanged during acipimox. Residual lipid oxidation increased significantly during exercise in both absolute and relative terms. Changes in selected cellular enzymes and proteins provided no explanations for kinetic changes. In conclusion, suppressed FFA availability blunts the effect of exercise on VLDL-TG secretion and modifies the contribution of lipid sources for oxidation.
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway; and.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Nellemann
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark;
authors.forename: Esben
authors.initials: E
authors.lastname: Søndergaard
authors.affiliation: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway; and.
authors.forename: Jørgen
authors.initials: J
authors.lastname: Jensen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark;
authors.forename: Steen Bønløkke
authors.initials: SB
authors.lastname: Pedersen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; Research Laboratory for Biochemical Pathology, Institute for Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Jessen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark;
authors.forename: Jens Otto Lunde
authors.initials: JO
authors.lastname: Jørgensen
authors.affiliation: Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark; nielsen.soren@dadlnet.dk.
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D006801:Humans; D000960:Hypolipidemic Agents / Q000008:administration & dosage*; D008066:Lipolysis / Q000187:drug effects / Q000502:physiology*; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D050177:Overweight / Q000378:metabolism*; D019308:Palmitic Acid / Q000378:metabolism; D011719:Pyrazines / Q000008:administration & dosage*; D014280:Triglycerides / Q000378:metabolism; D055815:Young Adult
chemical_list: D000960:Hypolipidemic Agents; D008079:Lipoproteins, VLDL; D011719:Pyrazines; D014280:Triglycerides; D019308:Palmitic Acid; C027696:acipimox
keywords: antilipolysis; exercise; lipid oxidation; very low-density lipoprotein