title: Remote cardioprotection by transfer of coronary effluent from ischemic preconditioned rabbit heart preserves mitochondrial integrity and function via adenosine receptor activation.
abstract: BACKGROUND
  Coronary effluent from an isolated perfused heart undergoing ischemic preconditioning can be transferred to precondition another naïve isolated heart. We investigated the effects of this effluent on mitochondrial integrity and function following a global infarct model of ischemia/reperfusion and the role of adenosine in this model of remote preconditioning.
  
  
  RESULTS
  Coronary effluent from isolated perfused rabbit hearts was collected prior to (control effluent) and during three cycles of 5-min ischemia and 10-min reperfusion (IPC effluent). Adenosine concentration was significantly increased in IPC effluent (2.6 ± 1.1 μM) versus control effluent (0.21 ± 0.06 μM, P < 0.01). Infarct size (% necrotic LV mass) after 30-min global ischemia and 90-min reperfusion was significantly reduced in hearts preconditioned with IPC effluent (IPC(eff), 23 ± 7 %) and control effluent supplemented with 2.5 μM exogenous adenosine (C(eff)+ 2.5 μM ADO, 25 ± 10 %) when compared to control effluent perfused hearts (C(eff), 41 ± 8 %, P < 0.05). Compared to C(eff) mitochondria, IPC(eff) mitochondria had preserved complex I/State3 and complex IV/State 3 respiration and outer membrane integrity, and reduced cytochrome c release. In contrast, C(eff) + 2.5 μM ADO mitochondria had improved state 2 respiration and coupling to oxidative phosphorylation, reduced reactive oxygen species production and preserved outer membrane integrity. Administration of adenosine receptor blocker 8-(p-sulfophenyl)theophylline abolished the infarct limiting effect (46 ± 7 %) and the mitochondrial integrity and function preservation of IPC effluent.
  
  
  CONCLUSIONS
  Remote cardioprotection by IPC effluent preserves mitochondrial integrity and function in an adenosine receptor dependent mechanism, and although infarct size reduction can be mimicked by adenosine, IPC effluent contains additional factor(s) contributing to modulation of the mitochondrial response to ischemia/reperfusion injury.
authors.affiliation: Division of Cardiovascular Surgery, Hospital for Sick Children/University of Toronto, 555 University Avenue, Toronto, Ontario, Canada, M5G 1X8.
authors.forename: Chung Ho
authors.initials: CH
authors.lastname: Leung
authors.forename: Lixing
authors.initials: L
authors.lastname: Wang
authors.forename: Jan M
authors.initials: JM
authors.lastname: Nielsen
authors.forename: Michael B
authors.initials: MB
authors.lastname: Tropak
authors.forename: Yana Y
authors.initials: YY
authors.lastname: Fu
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kato
authors.forename: John
authors.initials: J
authors.lastname: Callahan
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Redington
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Caldarone
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000818:Animals; D004195:Disease Models, Animal; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods*; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D009203:Myocardial Infarction / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D018047:Receptors, Purinergic P1; C031433:8-(4-sulfophenyl)theophylline; D013806:Theophylline; D000241:Adenosine