title: Continued depression of maximal oxygen consumption and mitochondrial proteomic expression despite successful coronary artery bypass grafting in a swine model of hibernation.
abstract: OBJECTIVE
  Clinical studies indicate incomplete functional recovery of hibernating myocardium after coronary artery bypass grafting. We hypothesized that persistent contractile abnormalities after coronary artery bypass grafting are associated with decreased mitochondrial proteins involving electron transport chain that might limit maximal oxygen consumption.
  
  
  METHODS
  Seven pigs with hibernating myocardium underwent off-pump revascularization with left internal thoracic artery to mid left anterior descending artery. At 4 weeks, left internal thoracic artery anastomosis was patent by multidetector computed tomography. Regional function (transthoracic echocardiography) and blood flow (microspheres) were assessed at rest and during high-dose dobutamine (40 μg/[kg · min]). Expression of electron transport chain proteins was analyzed with isobaric tags for relative and absolute quantification.
  
  
  RESULTS
  After revascularization, multidetector computed tomography confirmed severe left anterior descending stenosis and patent left internal thoracic artery graft. Regional function and blood flow normalized at rest; however, function in left anterior descending distribution remained depressed relative to remote regions, and myocardial blood flow in that region did not increase normally when challenged with high-work state. Concomitant with reduced maximal blood flow response in left anterior descending region was more than 40% reduction in electron transport chain proteins essential to adenosine triphosphate production.
  
  
  CONCLUSIONS
  Despite successful revascularization of hibernating myocardium, regional function and blood flow remained depressed during catecholamine stress. Electron transport chain proteins known to be downregulated during adaptive process within hibernating myocardium did not normalize after revascularization. These data demonstrate a potential bioenergetic cause of persistent dysfunction and heart failure within successfully revascularized hibernating myocardium.
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn 55417, USA. kelly071@umn.edu
authors.forename: Rosemary F
authors.initials: RF
authors.lastname: Kelly
authors.forename: Jesús A
authors.initials: JA
authors.lastname: Cabrera
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Ziemba
authors.forename: Melanie
authors.initials: M
authors.lastname: Crampton
authors.forename: Lorraine B
authors.initials: LB
authors.lastname: Anderson
authors.forename: Edward O
authors.initials: EO
authors.lastname: McFalls
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Ward
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists / Q000008:administration & dosage; D000818:Animals; D001783:Blood Flow Velocity; D017023:Coronary Angiography / Q000379:methods; D001026:Coronary Artery Bypass; D003326:Coronary Circulation; D004195:Disease Models, Animal; D004280:Dobutamine / Q000008:administration & dosage; D015536:Down-Regulation; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D017682:Myocardial Stunning / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010101:Oxygen Consumption; D040901:Proteomics / Q000379:methods; D013552:Swine; D014057:Tomography, X-Ray Computed; D014654:Vascular Patency; D016277:Ventricular Function, Left
chemical_list: D058665:Adrenergic beta-1 Receptor Agonists; D045222:Electron Transport Chain Complex Proteins; D024101:Mitochondrial Proteins; D004280:Dobutamine