Production of interleukin-6 in contracting human skeletal muscles can account for the exercise-induced increase in plasma interleukin-6

Authors

  • Adam Steensberg,

    1. The Copenhagen Muscle Research Centre and University of Copenhagen, Copenhagen, Denmark
    2. The Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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  • Gerrit van Hall,

    1. The Copenhagen Muscle Research Centre and University of Copenhagen, Copenhagen, Denmark
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  • Takuya Osada,

    1. The Copenhagen Muscle Research Centre and University of Copenhagen, Copenhagen, Denmark
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  • Massimo Sacchetti,

    1. The Copenhagen Muscle Research Centre and University of Copenhagen, Copenhagen, Denmark
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  • Bengt Saltin,

    1. The Copenhagen Muscle Research Centre and University of Copenhagen, Copenhagen, Denmark
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  • Bente Klarlund Pedersen

    Corresponding author
    1. The Copenhagen Muscle Research Centre and University of Copenhagen, Copenhagen, Denmark
    2. The Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
    • Corresponding author
      B. Klarlund Pedersen: The Department of Infectious Diseases and The Copenhagen Muscle Research Centre, Rigshospitalet 7652, Blegdamsvej 9, DK-2100 Copenhagen N, Denmark. Email: bkp@rh.dk

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Abstract

  • 1Plasma 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.
  • 2This 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).
  • 3Arterial 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).
  • 4The 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.

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