title: Interleukin-6 production in contracting human skeletal muscle is influenced by pre-exercise muscle glycogen content.
abstract: 1. Prolonged exercise results in a progressive decline in glycogen content and a concomitant increase in the release of the cytokine interleukin-6 (IL-6) from contracting muscle. This study tests the hypothesis that the exercise-induced IL-6 release from contracting muscle is linked to the intramuscular glycogen availability. 2. Seven men performed 5 h of a two-legged knee-extensor exercise, with one leg with normal, and one leg with reduced, muscle glycogen content. Muscle biopsies were obtained before (pre-ex), immediately after (end-ex) and 3 h into recovery (3 h rec) from exercise in both legs. In addition, catheters were placed in one femoral artery and both femoral veins and blood was sampled from these catheters prior to exercise and at 1 h intervals during exercise and into recovery. 3. Pre-exercise glycogen content was lower in the glycogen-depleted leg compared with the control leg. Intramuscular IL-6 mRNA levels increased with exercise in both legs, but this increase was augmented in the leg having the lowest glycogen content at end-ex. The arterial plasma concentration of IL-6 increased from 0.6 +/- 0.1 ng x l(-1) pre-ex to 21.7 +/- 5.6 ng x l(-1) end-ex. The depleted leg had already released IL-6 after 1 h (4.38 +/- 2.80 ng x min(-1) (P < 0.05)), whereas no significant release was observed in the control leg (0.36 +/- 0.14 ng x min(-1)). A significant net IL-6 release was not observed until 2 h in the control leg. 4. This study demonstrates that glycogen availability is associated with alterations in the rate of IL-6 production and release in contracting skeletal muscle.
authors.affiliation: The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Steensberg
authors.forename: M A
authors.initials: MA
authors.lastname: Febbraio
authors.forename: T
authors.initials: T
authors.lastname: Osada
authors.forename: P
authors.initials: P
authors.lastname: Schjerling
authors.forename: G
authors.initials: G
authors.lastname: van Hall
authors.forename: B
authors.initials: B
authors.lastname: Saltin
authors.forename: B K
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D001682:Biological Availability; D015444:Exercise / Q000502:physiology; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis*; D007717:Knee / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*
chemical_list: D015850:Interleukin-6; D006003:Glycogen