Ischemic preconditioning decreases mitochondrial proton leak and reactive oxygen species production in the postischemic heart

Ricardo Quarrie, Brandon M. Cramer, Daniel S. Lee, Gregory E. Steinbaugh, Warren Erdahl, Douglas R. Pfeiffer, Jay L. Zweier, Juan A. Crestanello

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Background: Proton leak (H+ leak) dissipates mitochondrial membrane potential (mΔΨ) through the re-entry of protons into the mitochondrial matrix independent of ATP synthase. Changes in H+ leak may affect reactive oxygen species (ROS) production. We measured H+ leak and ROS production during ischemia-reperfusion and ischemic preconditioning (IPC) and examined how changing mitochondrial respiration affected mΔΨ and ROS production. Materials and Methods: Isolated rat hearts (n = 6/group) were subjected to either control-IR or IPC. Rate pressure product (RPP) was measured. Mitochondria were isolated at end reperfusion. Respiration was measured by polarography and titrated with increasing concentrations of malonate (0.5-2 mM). mΔΨ was measured using a tetraphenylphosphonium electrode. H+ leak is the respiratory rate required to maintain membrane potential at -150 mV in the presence of oligomycin-A. Mitochondrial complex III ROS production was measured by fluorometry using Amplex-red. Results: IPC improved recovery of RPP at end reperfusion (63% ± 4% versus 21% ± 2% in control-IR, P <0.05). Ischemia-reperfusion caused increased H+ leak (94 ± 12 versus 31 ± 1 nmol O/mg protein/min in non-ischemic control, P <0.05). IPC attenuates these increases (55 ± 9 nmol O/mg protein/min, P <0.05 versus control-IR). IPC reduced mitochondrial ROS production compared with control-IR (31 ± 2 versus 40 ± 3 nmol/mg protein/min, P <0.05). As mitochondrial respiration decreased, mΔΨ and mitochondrial ROS production also decreased. ROS production remained lower in IPC than in control-IR for all mΔΨ and respiration rates. Conclusions: Increasing H+ leak is not associated with decreased ROS production. IPC decreases both the magnitude of H+ leak and ROS production after ischemia-reperfusion.

Original languageEnglish (US)
Pages (from-to)5-14
Number of pages10
JournalJournal of Surgical Research
Issue number1
StatePublished - Jan 2011
Externally publishedYes


  • Heart
  • Ischemia
  • Mitochondria
  • Proton leak
  • Reactive oxygen species
  • Reperfusion
  • Uncoupling

ASJC Scopus subject areas

  • Surgery


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