title: Exenatide alters myocardial glucose transport and uptake depending on insulin resistance and increases myocardial blood flow in patients with type 2 diabetes.
abstract: BACKGROUND
  Glucagon-like peptide-1 (GLP-1) and GLP-1 receptor agonists provide beneficial cardiovascular effects by protecting against ischemia and reperfusion injury. Type 2 diabetes mellitus patients have reduced glycolysis in the heart.
  
  
  OBJECTIVE
  We hypothesized that cardioprotection by GLP-1 is achieved through increased glucose availability and utilization and aimed to assess the effect of exenatide, a synthetic GLP-1 receptor agonist, on myocardial glucose uptake (MGU), myocardial glucose transport, and myocardial blood flow (MBF).
  
  
  METHODS
  We conducted a randomized, double-blinded, placebo-controlled crossover study in eight male, insulin-naive, type 2 diabetes mellitus patients without coronary artery disease. Positron emission tomography was used to determine the effect of exenatide on MGU and MBF during a pituitary-pancreatic hyperglycemic clamp with (18)F-fluorodeoxyglucose and (13)N-ammonia as tracers.
  
  
  RESULTS
  Overall, exenatide did not alter MGU. However, regression analysis revealed that exenatide altered initial clearance of glucose over the membrane of cardiomyocytes and MGU, depending on the level of insulin resistance (P = 0.017 and 0.010, respectively). Exenatide increased MBF from 0.73 ± 0.094 to 0.85 ± 0.091 ml/g · min (P = 0.0056). Except for an increase in C-peptide levels, no differences in circulating hormones or metabolites were found.
  
  
  CONCLUSIONS
  The action of exenatide as an activator or inhibitor of the glucose transport and glucose uptake in cardiomyocytes is dependent on baseline activity of glucose transport and insulin resistance. Exenatide increases MBF without changing MGU.
authors.affiliation: Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, DK-8000 Aarhus C, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Gejl
authors.forename: H M
authors.initials: HM
authors.lastname: Søndergaard
authors.forename: C
authors.initials: C
authors.lastname: Stecher
authors.forename: B M
authors.initials: BM
authors.lastname: Bibby
authors.forename: N
authors.initials: N
authors.lastname: Møller
authors.forename: H E
authors.initials: HE
authors.lastname: Bøtker
authors.forename: S B
authors.initials: SB
authors.lastname: Hansen
authors.forename: A
authors.initials: A
authors.lastname: Gjedde
authors.forename: J
authors.initials: J
authors.lastname: Rungby
authors.forename: B
authors.initials: B
authors.lastname: Brock
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D003326:Coronary Circulation / Q000187:drug effects*; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D004311:Double-Blind Method; D000077270:Exenatide; D005947:Glucose / Q000378:metabolism / Q000493:pharmacokinetics*; D006321:Heart / Q000187:drug effects; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010455:Peptides / Q000494:pharmacology*; D010919:Placebos; D049268:Positron-Emission Tomography; D012039:Regional Blood Flow / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D014688:Venoms / Q000494:pharmacology*
chemical_list: D007004:Hypoglycemic Agents; D010455:Peptides; D010919:Placebos; D014688:Venoms; D000077270:Exenatide; D005947:Glucose