title: Acute resistance exercise increases the expression of chemotactic factors within skeletal muscle.
abstract: BACKGROUND
  Intense resistance exercise causes mechanical loading of skeletal muscle, followed by muscle adaptation. Chemotactic factors likely play an important role in these processes.
  
  
  OBJECTIVE
  We investigated the time course of changes in the expression and tissue localization of several key chemotactic factors in skeletal muscle during the early phase of recovery following resistance exercise.
  
  
  METHODS
  Muscle biopsy samples were obtained from vastus lateralis of eight untrained men (22 ± 0.5 years) before and 2, 4 and 24 h after three sets of leg press, squat and leg extension at 80 % 1-RM.
  
  
  RESULTS
  Monocyte chemotactic protein-1 (95×), interleukin-8 (2,300×), IL-6 (317×), urokinase-type plasminogen activator (15×), vascular endothelial growth factor (2×) and fractalkine (2.5×) mRNA was significantly elevated 2 h post-exercise. Interleukin-8 (38×) and interleukin-6 (58×) protein was also significantly elevated 2 h post-exercise, while monocyte chemotactic protein-1 protein was significantly elevated at 2 h (22×) and 4 h (21×) post-exercise. Monocyte chemotactic protein-1 and interleukin-8 were expressed by cells residing in the interstitial space between muscle fibers and, in some cases, were co-localized with CD68 + macrophages, PAX7 + satellite cells and blood vessels. However, the patterns of staining were inconclusive and not consistent.
  
  
  CONCLUSIONS
  In conclusion, resistance exercise stimulated a marked increase in the mRNA and protein expression of various chemotactic factors in skeletal muscle. Myofibers were not the dominant source of these factors. These findings suggest that chemotactic factors regulate remodeling/adaptation of skeletal muscle during the early phase of recovery following resistance exercise.
authors: Centre for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
authors: Paul A
authors: PA
authors: Della Gatta
authors: David
authors: D
authors: Cameron-Smith
authors: Jonathan M
authors: JM
authors: Peake
mesh_terms: D016022:Case-Control Studies; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D054428:Chemokine CX3CL1 / Q000235:genetics / Q000378:metabolism*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D055070:Resistance Training; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D055815:Young Adult
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D054428:Chemokine CX3CL1; D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D014568:Urokinase-Type Plasminogen Activator