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This Article Full Text Full Text (PDF) All Versions of this Article: 92/1/233    most recent expphysiol.2006.034769v1 Alert me when this article is cited Alert me if a correction is posted 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 Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Frydelund-Larsen, L. Articles by Pedersen, B. K. Search for Related Content PubMed PubMed Citation Articles by Frydelund-Larsen, L. Articles by Pedersen, B. K.

¹ The Centre of Inflammation and Metabolism at Department of Infectious Diseases and Copenhagen Muscle Research Center, Rigshospitalet and Faculty of Health Sciences, University of Copenhagen, Denmark ² Section of Neuroprotection, Institute of Neurobiology and Molecular Pharmacology, Faculty of Health Sciences, University of Copenhagen, Denmark

Exercise induces a marked increase in interleukin-8 (IL-8) mRNA and protein expression within skeletal muscle fibres. Interleukin-8 belongs to a subfamily of CXC chemokines containing a Glu-Leu-Arg (ELR) motif. CXC chemokines with ELR motifs are potent angiogenic factors in vivo, and IL-8 has been shown to act as an angiogenic factor in human microvascular endothelial cells by binding to the CXC receptor 2 (CXCR2). In the present study, we examined the expression of the interleukin-8 receptor CXCR2 in human skeletal muscle biopsies after concentric exercise. Healthy volunteers were randomized to either 3 h of cycle ergometer exercise at 60% of maximum oxygen uptake (n = 8) or rest (n = 7). Muscle biopsy samples were obtained from the vastus lateralis before exercise (0 h), immediately after exercise (3 h), and at 4.5, 6, 9 and 24 h. Skeletal muscle CXCR2 mRNA increased significantly in response to exercise (3 and 4.5 h) when compared with pre-exercise samples. Expression of the CXCR2 protein was low in skeletal muscle biopsies before exercise and at the end of the exercise period (3 h). However, at 4.5–9 h, an increase in CXCR2 protein was seen in the vascular endothelium, and also slightly within the muscle fibres, as determined by immunohistochemistry. The present study demonstrates that concentric exercise induces CXCR2 mRNA and protein expression in the vascular endothelial cells of the muscle fibres. These findings suggest that muscle-derived IL-8 may act locally to stimulate angiogenesis through CXCR2 receptor signalling.

(Received 9 July 2006; accepted after revision 5 October 2006; first published online 9 October 2006)
Corresponding author B. K. Pedersen: Centre of Inflammation and Metabolism, Rigshospitalet – Section 7641, Blegdamsvej 9, DK-2100, Copenhagen, Denmark. Email: bkp{at}rh.dk