title: Frequent biomarker analysis in the isolated perfused heart reveals two distinct phases of reperfusion injury.
abstract: BACKGROUND
  Reperfusion injury and its modulation are incompletely characterized. The purpose of the present study was to characterize the dynamics of reperfusion injury by portraying the temporal release of lactate dehydrogenase (LDH) during ischemia-reperfusion injury in an isolated heart model.
  
  
  METHODS
  We studied infarct size and LDH release in the following groups: I) Effect of reperfusion length was evaluated in 79 rats subjected to 40 minute ischemia and 60, 90, 120 or 180 minute reperfusion and a) ischemic preconditioning (IPC) or b) No IPC (control). II) LDH release kinetics was studied in 6 rats subjected to calcium-paradox to verify the applicability of LDH as a dynamic marker of cellular injury. III) Ischemia-reperfusion injury modification was studied in 36 rats subjected to: a) ischemic postconditioning, b) prolonged ischemia, c) Reperfusion Injury Salvage Kinase (RISK) pathway inhibition with wortmannin in IPC hearts, d) RISK activation with insulin or e) mitochondrial permeability transition pore (mPTP) inhibition with cyclosporine A.
  
  
  RESULTS
  Infarct size increased from 60 to 180 minute reperfusion in control hearts. LDH was released in two separate peaks from 2 to 20 and 30 to 120 min of reperfusion. IPC attenuated both peaks. Postconditioning and agents known to modify reperfusion injury attenuated the second peak.
  
  
  CONCLUSIONS
  Frequent measurement of myocardial ischemia markers for 120 min of reperfusion allows identification of two phases of reperfusion injury that are affected by cardioprotective stimuli. The second phase contributes significantly to final infarct size, which is modifiable and a potential target for cardioprotective interventions.
authors: Department of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark; Institute of Clinical Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark. Electronic address: jonas.povlsen@ki.au.dk.
authors: Jonas Agerlund
authors: JA
authors: Povlsen
authors: Department of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark; Institute of Clinical Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors: Bo
authors: B
authors: Løfgren
authors: Department of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark; Institute of Clinical Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors: Christian
authors: C
authors: Dalgas
authors: Department of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark; Institute of Clinical Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors: Nichlas Riise
authors: NR
authors: Jespersen
authors: Department of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark; Institute of Clinical Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors: Jacob
authors: J
authors: Johnsen
authors: Department of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark; Institute of Clinical Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors: Hans Erik
authors: HE
authors: Bøtker
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism*; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism* / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D015415:Biomarkers; D007770:L-Lactate Dehydrogenase
keywords: Biomarker; Cardioprotection; Ischemia–reperfusion injury; Ischemic preconditioning; Reperfusion injury