Remote Cardioprotection by Transfer of Coronary Effluent from Ischemic Preconditioned Rabbit Heart Preserves Mitochondrial Integrity and Function via Adenosine Receptor Activation

Background Coronary effluent from an isolated perfused heart undergoing ischemic preconditioning can be transferred to precondition another na < ve 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. 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 mu M) versus control effluent (0.21 +/- 0.06 mu M, 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 (IPCeff, 23 +/- 7 %) and control effluent supplemented with 2.5 mu M exogenous adenosine (C-eff + 2.5 mu M ADO, 25 +/- 10 %) when compared to control effluent perfused hearts (C-eff, 41 +/- 8 %, P < 0.05). Compared to C-eff mitochondria, IPCeff 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 mu M 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. 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.