title: IL-6 and TNF-alpha expression in, and release from, contracting human skeletal muscle.
abstract: The aim of the present study was to examine whether IL-6 and TNF-alpha are expressed in, and released from, human skeletal muscle during exercise. We hypothesized that the skeletal muscle will release IL-6, but not TNF-alpha, during exercise because of previous observations that TNF-alpha negatively affects glucose uptake in skeletal muscle. Six healthy, male subjects performed 180 min of two-legged knee-extensor exercise. Muscle samples were obtained from the vastus lateralis of one limb. In addition, blood samples were obtained from a femoral artery and vein. Plasma was analyzed for IL-6 and TNF-alpha. We detected both IL-6 and TNF-alpha mRNA in resting muscle samples, and whereas IL-6 increased (P < 0.05) approximately 100-fold throughout exercise, no significant increase in TNF-alpha mRNA was observed. Arterial plasma TNF-alpha did not increase during exercise. Furthermore, there was no net release of TNF-alpha either before or during exercise. In contrast, IL-6 increased throughout exercise in arterial plasma, and a net IL-6 release from the contracting limb was observed after 120 min of exercise (P < 0.05).
authors.affiliation: Copenhagen Muscle Research Centre and Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, DK-2100 Copenhagen, Denmark.
authors.forename: Adam
authors.initials: A
authors.lastname: Steensberg
authors.forename: Charlotte
authors.initials: C
authors.lastname: Keller
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Starkie
authors.forename: Takuya
authors.initials: T
authors.lastname: Osada
authors.forename: Mark A
authors.initials: MA
authors.lastname: Febbraio
authors.forename: Bente Klarlund
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005263:Femoral Artery / Q000502:physiology; D005268:Femoral Vein / Q000502:physiology; D006003:Glycogen / Q000032:analysis / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D007866:Leg / Q000098:blood supply / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D005082:Physical Exertion / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D012016:Reference Values; D012039:Regional Blood Flow; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D015850:Interleukin-6; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D006003:Glycogen