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This Article Full Text Full Text (PDF) All Versions of this Article: 586/8/2195    most recent jphysiol.2007.149781v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Broholm, C. Articles by Pedersen, B. K. PubMed PubMed Citation Articles by Broholm, C. Articles by Pedersen, B. K. Related Collections Skeletal Muscle and Exercise

¹ Centre of Inflammation and Metabolism, Department of Infectious Diseases
² Department of Orthopaedic Surgery, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Denmark

The leukaemia inhibitory factor (LIF) belongs to the interleukin (IL)-6 cytokine superfamily and is constitutively expressed in skeletal muscle. We tested the hypothesis that LIF expression in human skeletal muscle is regulated by exercise. Fifteen healthy young male volunteers performed either 3 h of cycle ergometer exercise at 60% of (n = 8) or rested (n = 7). Muscle biopsies were obtained from the vastus lateralis prior to exercise, immediately after exercise, and at 1.5, 3, 6 and 24 h post exercise. Control subjects had biopsy samples taken at the same time points as during the exercise trial. Skeletal muscle LIF mRNA increased immediately after the exercise and declined gradually during recovery. However, LIF protein was unchanged at the investigated time points. Moreover, we tested the hypothesis that LIF mRNA and protein expressions are modulated by calcium (Ca²⁺) in primary human skeletal myocytes. Treatment of myocytes with the Ca²⁺ ionophore, ionomycin, for 6 h resulted in an increase in both LIF mRNA and LIF protein levels. This finding suggests that Ca²⁺ may be involved in the regulation of LIF in endurance-exercised skeletal muscle. In conclusion, primary human skeletal myocytes have the capability to produce LIF in response to ionomycin stimulation and LIF mRNA levels increase in skeletal muscle following concentric exercise. The finding that the increase in LIF mRNA levels is not followed by a similar increase in skeletal muscle LIF protein suggests that other exercise stimuli or repetitive stimuli are necessary in order to induce a detectable accumulation of LIF protein.

(Received 13 December 2007; accepted after revision 20 February 2008; first published online 21 February 2008)
Corresponding author B. K. Pedersen: Centre of Inflammation and Metabolism, Rigshospitalet – Section 7641, Tagensvej 20, DK-2100, Copenhagen, Denmark. Email: bkp{at}rh.dk