title: Are abnormalities in sarcoplasmic reticulum calcium cycling properties involved in trapezius myalgia?: case studies on three females.
abstract: OBJECTIVE
  The aim of this study was to demonstrate the feasibility of using samples obtained through muscle biopsy to assess a wide range of cellular properties, some of which may be abnormal in myalgia. Given the recent emphasis on the role of excitation-contraction coupling in health and disease, special emphasis is given to the characterization of the properties involved in this process.
  
  
  METHODS
  Tissue samples were obtained from the upper portion of the descending trapezius muscle in three female patients (PAT) with clinically diagnosed myalgia and assessed for a spectrum of properties related to substrate use, energy production, and excitation-contraction coupling and were compared with samples from three healthy controls.
  
  
  RESULTS
  At the level of organization of the metabolic pathways, all PAT generally displayed normal activities of enzymes representing the potential for oxidative phosphorylation, glucose phosphorylation, glycolysis, and lactate oxidation. In contrast, a reduced potential was observed in PAT for both fat oxidation (-20%) and high-energy phosphate transfer (-38%). For excitation-contraction coupling, PAT had a compromised sarcoplasmic reticulum maximal Ca-ATPase activity (-21%), Ca uptake (-44%), and sarcoplasmic endopleasmic reticulum (SERCA) expression for both SERCA1a (-16%) and SERCA2a (-17%), which were accompanied by a lower phase 2 Ca release (-45%). The Na-K-ATPase concentration, the enzyme-regulating membrane excitability via active Na and K seemed elevated (+25%) in PAT.
  
  
  CONCLUSIONS
  These results demonstrate the feasibility of analyzing tissue samples for a wide range of properties and provide a rationale for studies examining the cellular basis of myalgia with particular emphasis on sarcoplasmic reticulum Ca cycling, given the latter's role in regulating a wide range of cellular functions.
authors.affiliation: Department of Kinesiology, University of Waterloo, Ontario, Canada.
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Green
authors.forename: Patti
authors.initials: P
authors.lastname: Galvin
authors.forename: Don A
authors.initials: DA
authors.lastname: Ranney
authors.forename: Heather
authors.initials: H
authors.lastname: Tick
authors.forename: Jing
authors.initials: J
authors.lastname: Ouyang
mesh_terms: D000328:Adult; D015220:Calcium Channels / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009135:Muscular Diseases / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D019547:Neck Pain / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism* / Q000473:pathology*; D020069:Shoulder Pain / Q000209:etiology / Q000378:metabolism* / Q000473:pathology
chemical_list: D015220:Calcium Channels