title: Production of interleukin-6 in contracting human skeletal muscles can account for the exercise-induced increase in plasma interleukin-6.
abstract: 1. Plasma interleukin (IL)-6 concentration is increased with exercise and it has been demonstrated that contracting muscles can produce IL-The question addressed in the present study was whether the IL-6 production by contracting skeletal muscle is of such a magnitude that it can account for the IL-6 accumulating in the blood. 2. This was studied in six healthy males, who performed one-legged dynamic knee extensor exercise for 5 h at 25 W, which represented 40% of peak power output (Wmax). Arterial-femoral venous (a-fv) differences over the exercising and the resting leg were obtained before and every hour during the exercise. Leg blood flow was measured in parallel by the ultrasound Doppler technique. IL-6 was measured by enzyme-linked immunosorbent assay (ELISA). 3. Arterial plasma concentrations for IL-6 increased 19-fold compared to rest. The a-fv difference for IL-6 over the exercising leg followed the same pattern as did the net IL-6 release. Over the resting leg, there was no significant a-fv difference or net IL-6 release. The work was produced by 2.5 kg of active muscle, which means that during the last 2 h of exercise, the median IL-6 production was 6.8 ng min-1 (kg active muscle)-1 (range, 3.96-9.69 ng min-1 kg-1). 4. The net IL-6 release from the muscle over the last 2 h of exercise was 17-fold higher than the elevation in arterial IL-6 concentration and at 5 h of exercise the net release during 1 min was half of the IL-6 content in the plasma. This indicates a very high turnover of IL-6 during muscular exercise. We suggest that IL-6 produced by skeletal contracting muscle contributes to the maintenance of glucose homeostasis during prolonged exercise.
authors.affiliation: The Copenhagen Muscle Research Centre and The Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Steensberg
authors.forename: G
authors.initials: G
authors.lastname: van Hall
authors.forename: T
authors.initials: T
authors.lastname: Osada
authors.forename: M
authors.initials: M
authors.lastname: Sacchetti
authors.forename: B
authors.initials: B
authors.lastname: Saltin
authors.forename: B
authors.initials: B
authors.lastname: Klarlund Pedersen
mesh_terms: D000328:Adult; D016552:Ergometry; D015444:Exercise / Q000502:physiology*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000097:blood; D007866:Leg / Q000098:blood supply; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology; D013997:Time Factors
chemical_list: D015850:Interleukin-6