title: Analysis of proglycogen and macroglycogen content in muscle biopsy specimens obtained from horses.
abstract: OBJECTIVE
  To determine proglycogen (PG) and macroglycogen (MG) content in equine skeletal muscle and to compare 2 analytical methods (acid hydrolysis [AC] and PG plus MG determination) for measurement of total muscle glycogen content (Gly(tot)) in biopsy specimens.
  
  
  METHODS
  Muscle biopsy specimens obtained from 41 clinically normal horses.
  
  
  METHODS
  Forty-five muscle biopsy specimens obtained from the middle gluteal (n = 31) or triceps (14) muscle were analyzed, using AC and MG plus PG determination for Gly(tot). Variability within muscle biopsy specimens for each method was calculated from duplicate analyses of muscle specimens. In a second experiment, variation in MG and PG content between muscle biopsy specimens and the effect of sample collection depth on the concentration of MG and PG in the middle gluteal muscle was evaluated.
  
  
  RESULTS
  There was a strong correlation (r = 0.99) between Gly(tot) values obtained by use of AC and MG plus PG determination. Coefficients of variation for within- and between-specimen variability of Gly(tot) were approximately 4% for each method. The PG fraction was always in excess of the MG fraction. Biopsy specimens obtained from the superficial part of the middle gluteal muscle contained significantly more Gly(tot) and PG than specimens obtained from deeper parts.
  
  
  CONCLUSIONS
  This study confirms that MG and PG exist in equine skeletal muscle and can be measured reliably in biopsy samples. This technique could be applied in future studies to investigate glycogen metabolism in exercising horses and horses with glycogen-storage diseases.
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Canada.
authors.forename: Johan T
authors.initials: JT
authors.lastname: Bröjer
authors.forename: Henry R
authors.initials: HR
authors.lastname: Stämpfli
authors.forename: Terry E
authors.initials: TE
authors.lastname: Graham
mesh_terms: D000818:Animals; D001707:Biopsy, Needle / Q000379:methods / Q000662:veterinary; D005260:Female; D006003:Glycogen / Q000032:analysis / Q000378:metabolism*; D006736:Horses / Q000378:metabolism*; D006868:Hydrolysis; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D010472:Perchlorates / Q000737:chemistry; D012044:Regression Analysis; D015203:Reproducibility of Results
chemical_list: D010472:Perchlorates; D006003:Glycogen