title: Identification of proteins from interstitium of trapezius muscle in women with chronic myalgia using microdialysis in combination with proteomics.
abstract: BACKGROUND
  Microdialysis (MD) of the trapezius muscle has been an attractive technique to investigating small molecules and metabolites in chronic musculoskeletal pain in human. Large biomolecules such as proteins also cross the dialysis membrane of the catheters. In this study we have applied in vivo MD in combination with two dimensional gel electrophoresis (2-DE) and mass spectrometry to identify proteins in the extracellular fluid of the trapezius muscle.
  
  
  METHODS
  Dialysate from women with chronic trapezius myalgia (TM; n = 37), women with chronic wide spread pain (CWP; n = 18) and healthy controls (CON; n = 22) was collected from the trapezius muscle using a catheter with a cut-off point of 100 kDa. Proteins were separated by two-dimensional gel electrophoresis and visualized by silver staining. Detected proteins were identified by nano liquid chromatography in combination with tandem mass spectrometry.
  
  
  RESULTS
  Ninety-seven protein spots were identified from the interstitial fluid of the trapezius muscle; 48 proteins in TM and 30 proteins in CWP had concentrations at least two-fold higher or lower than in CON. The identified proteins pertain to several functional classes, e.g., proteins involved in inflammatory responses. Several of the identified proteins are known to be involved in processes of pain such as: creatine kinase, nerve growth factor, carbonic anhydrase, myoglobin, fatty acid binding protein and actin aortic smooth muscle.
  
  
  CONCLUSIONS
  In this study, by using in vivo microdialysis in combination with proteomics a large number of proteins in muscle interstitium have been identified. Several of the identified proteins were at least two-fold higher or lower in chronic pain patients. The applied techniques open up for the possibility of investigating protein changes associated with nociceptive processes of chronic myalgia.
authors.affiliation: Rehabilitation Medicine, Department of Medicine and Health Sciences, Faculty of Health Sciences, University of Linköping and Pain- and Rehabilitation Centre, County Council, Linköping, Sweden.
authors.forename: Patrik
authors.initials: P
authors.lastname: Olausson
authors.forename: Björn
authors.initials: B
authors.lastname: Gerdle
authors.forename: Nazdar
authors.initials: N
authors.lastname: Ghafouri
authors.forename: Britt
authors.initials: B
authors.lastname: Larsson
authors.forename: Bijar
authors.initials: B
authors.lastname: Ghafouri
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002908:Chronic Disease; D045604:Extracellular Fluid / Q000378:metabolism*; D005260:Female; D006801:Humans; D017551:Microdialysis; D008875:Middle Aged; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism* / Q000473:pathology*; D059352:Musculoskeletal Pain / Q000378:metabolism* / Q000473:pathology; D040901:Proteomics
chemical_list: D009124:Muscle Proteins