title: Remote ischemic preconditioning impairs ventricular function and increases infarct size after prolonged ischemia in the isolated neonatal rabbit heart.
abstract: OBJECTIVE
  Remote ischemic preconditioning (rIPC) reduces myocardial injury in adults and children undergoing cardiac surgery. We compared the effect of rIPC in adult and neonatal rabbits to investigate whether protection against ischemia-reperfusion injury can be achieved in the newborn heart by (1) in vivo rIPC and (2) dialysate from adult rabbits undergoing rIPC.
  
  
  METHODS
  Isolated hearts from newborn and adult rabbits were randomized into 3 subgroups (control, in vivo rIPC, and dialysate obtained from adult, remotely preconditioned rabbits). Remote preconditioning was induced by four 5-minute cycles of lower limb ischemia. Left ventricular (LV) function was assessed using a balloon-tipped catheter, glycolytic flux by tracer kinetics, and infarct size by tetrazolium staining. Isolated hearts underwent stabilization while perfused with standard Krebs-Henseleit buffer (control and in vivo rIPC) or Krebs-Henseleit buffer with added dialysate, followed by global no-flow ischemia and reperfusion.
  
  
  RESULTS
  Within the age groups, the baseline LV function was similar in all subgroups. In the adult rabbit hearts, rIPC and rIPC dialysate attenuated glycolytic flux and protected against ischemia-reperfusion injury, with better-preserved LV function compared with that of the controls. In contrast, in the neonatal hearts, the glycolytic flux was lower and LV function was better preserved in the controls than in the rIPC and dialysate groups. In the adult hearts, the infarct size was reduced in the rIPC and dialysate groups compared with that in the controls. In the neonatal hearts, the infarct size was smaller in the controls than in the rIPC and dialysate groups.
  
  
  CONCLUSIONS
  Remote ischemic preconditioning does not protect against ischemia-reperfusion injury in isolated newborn rabbit hearts and might even cause deleterious effects. Similar adverse effects were induced by dialysate from remotely preconditioned adult rabbits.
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgaardsvej, Aarhus N, Aarhus, Denmark. Electronic address: Michael.rahbek@ki.au.dk.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Schmidt
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgaardsvej, Aarhus N, Aarhus, Denmark.
authors.forename: Nicolaj B
authors.initials: NB
authors.lastname: Støttrup
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgaardsvej, Aarhus N, Aarhus, Denmark.
authors.forename: Marie M
authors.initials: MM
authors.lastname: Michelsen
authors.affiliation: Department of Cardiology, John Radcliffe Hospital, Headington, Oxford, United Kingdom.
authors.forename: Hussain
authors.initials: H
authors.lastname: Contractor
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgaardsvej, Aarhus N, Aarhus, Denmark.
authors.forename: Keld E
authors.initials: KE
authors.lastname: Sørensen
authors.affiliation: Department of Cardiology, John Radcliffe Hospital, Headington, Oxford, United Kingdom.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Kharbanda
authors.affiliation: Division of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Redington
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby, Brendstrupgaardsvej, Aarhus N, Aarhus, Denmark.
authors.forename: Hans E
authors.initials: HE
authors.lastname: Bøtker
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D006019:Glycolysis; D019194:Ischemic Preconditioning / Q000009:adverse effects*; D035002:Lower Extremity / Q000098:blood supply*; D009203:Myocardial Infarction / Q000209:etiology* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D015428:Myocardial Reperfusion Injury / Q000209:etiology* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D010477:Perfusion; D011817:Rabbits; D012039:Regional Blood Flow; D012307:Risk Factors; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000209:etiology* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D016277:Ventricular Function, Left