title: Glibenclamide effects on reperfusion-induced malignant arrhythmias and left ventricular mechanical recovery from stunning in conscious sheep.
abstract: BACKGROUND
  Sulfonylureas have been associated with a high incidence of cardiovascular death in diabetic patients treated with these drugs. Although the evidence on the cardiovascular effects of sulfonylureas is contradictory and scarce, many experiments have shown that the second-generation compound glibenclamide has a protective effect on mechanical function and against generation of malignant arrhythmias.
  
  
  OBJECTIVE
  The purpose of this study was to assess whether glibenclamide elicits protection on postischemic myocardial functional recovery (stunning) and against reperfusion-induced arrhythmias in a conscious sheep model.
  
  
  METHODS
  Sheep were divided into three groups: control, glibenclamide (0.4 mg/kg) and vehicle. After a 12-min ischemic period, the heart was reperfused and recordings for index calculation were acquired during 2 h of reperfusion. Percent systolic wall thickening fraction (%WTH), radial diastolic compliance (CR), arrhythmia incidence and Bernauer's arrhythmia severity index (ASI) were calculated for each group.
  
  
  RESULTS
  Glibenclamide infusion had a high proarrhythmic action (ASI: glibenclamide 143, control 54 and vehicle 23; ANOVA P < 0.001 drug vs. control and vehicle) and a detrimental effect on regional systolic (%WTH: glibenclamide 26.9 +/- 6.7, control 65.7 +/- 3.5 and vehicle 68.6 +/- 5.6, ANOVA P < 0.01 drug vs. control and vehicle) and diastolic function (CR: glibenclamide 76.2 +/- 7.8, control 104.7 +/- 4.2 and vehicle 106 +/- 4.9, ANOVA P < 0.05 drug vs. control and vehicle) during reperfusion.
  
  
  CONCLUSIONS
  Glibenclamide infusion resulted in adverse cardiovascular effects. The combined deleterious effects on reperfusion-induced arrhythmias and on myocardial recovery from stunning could be the cause of the unexplained high mortality in diabetic patients treated with sulfonylurea derivatives. The mechanism involved seems to be the blockade of the cardiac ATP sensitive potassium (K-ATP) channel.
authors.affiliation: Department of Physiology, Pharmacology and Biochemistry. Favaloro University, Solis 453, 1078, Buenos Aires, Argentina. delvalle@favaloro.edu.ar
authors.forename: H F
authors.initials: HF
authors.lastname: del Valle
authors.forename: E C
authors.initials: EC
authors.lastname: Lascano
authors.forename: J A
authors.initials: JA
authors.lastname: Negroni
authors.forename: A J
authors.initials: AJ
authors.lastname: Crottogini
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000503:physiopathology; D005905:Glyburide / Q000633:toxicity*; D006439:Hemodynamics / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000633:toxicity*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D017202:Myocardial Ischemia / Q000503:physiopathology; D015425:Myocardial Reperfusion / Q000009:adverse effects*; D017682:Myocardial Stunning / Q000503:physiopathology*; D015221:Potassium Channels / Q000502:physiology; D012756:Sheep; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D007004:Hypoglycemic Agents; D015221:Potassium Channels; D000255:Adenosine Triphosphate; D005905:Glyburide