title: Effect of repeated oral administration of glucose and leucine immediately after exercise on plasma insulin concentration and glycogen synthesis in horses.
abstract: OBJECTIVE
  To determine whether repeated oral administration of glucose and leucine during the period immediately after intense exercise would increase the release of insulin and thereby enhance glycogen synthesis in horses.
  
  
  METHODS
  12 Standardbred horses.
  
  
  METHODS
  In a crossover study design, after glycogen-depleting exercise, horses received oral boluses of glucose (1 g/kg at 0, 2, and 4 hours) and leucine (0.1 g/kg at 0 and 4 hours) or boluses of water (10 mL/kg at 0, 2, and 4 hours; control treatment). Blood samples for determination of glucose, insulin, and leucine concentrations were collected prior to and during a 6-hour period immediately after exercise. Biopsy specimens of a gluteus muscle were obtained before and immediately after exercise and at 3, 6, and 24 hours after exercise for measurement of glycogen concentration.
  
  
  RESULTS
  When glucose and leucine were administered to the horses, plasma insulin concentration was significantly higher during the 6 hours immediately after exercise than it was when water was administered to the horses. Serum glucose concentration during the 4 hours immediately after exercise was significantly higher when glucose and leucine were administered than the serum glucose concentration when water was administered. Muscle glycogen concentrations did not differ between the 2 treatments during the 24 hours after exercise.
  
  
  CONCLUSIONS
  Synthesis of muscle glycogen after intense intermittent exercise was not enhanced by oral boluses of glucose and leucine after exercise despite pronounced increases in plasma insulin and serum glucose concentrations.
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden. johan.brojer@slu.se
authors.forename: Johan T
authors.initials: JT
authors.lastname: Bröjer
authors.forename: Katarina E A
authors.initials: KE
authors.lastname: Nostell
authors.forename: Birgitta
authors.initials: B
authors.lastname: Essén-Gustavsson
authors.forename: Ulf O
authors.initials: UO
authors.lastname: Hedenström
mesh_terms: D000284:Administration, Oral; D000818:Animals; D018592:Cross-Over Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D006003:Glycogen / Q000096:biosynthesis*; D006736:Horses / Q000097:blood* / Q000502:physiology; D007328:Insulin / Q000097:blood*; D007930:Leucine / Q000008:administration & dosage / Q000494:pharmacology*; D010805:Physical Conditioning, Animal / Q000379:methods*
chemical_list: D007328:Insulin; D006003:Glycogen; D007930:Leucine; D005947:Glucose