Mitochondrial uncoupling does not decrease reactive oxygen species production after ischemia-reperfusion

Ricardo Quarrie, Daniel S. Lee, Levy Reyes, Warren Erdahl, Douglas R. Pfeiffer, Jay L. Zweier, Juan A. Crestanello

Research output: Contribution to journalArticlepeer-review

Abstract

Cardiac ischemia-reperfusion (IR) leads to myocardial dysfunction by increasing production of reactive oxygen species (ROS). Mitochondrial H+ leak decreases ROS formation; it has been postulated that increasing H+ leak may be a mechanism of decreasing ROS production after IR. Ischemic preconditioning (IPC) decreases ROS formation after IR, but the mechanism is unknown. We hypothesize that pharmacologically increasing mitochondrial H+ leak would decrease ROS production after IR. We further hypothesize that IPC would be associated with an increase in the rate of H+ leak. Isolated male Sprague-Dawley rat hearts were subjected to either control or IPC. Mitochondria were isolated at end equilibration, end ischemia, and end reperfusion. Mitochondrial membrane potential (mΔΨ) was measured using a tetraphenylphosphonium electrode. Mitochondrial uncoupling was achieved by adding increasing concentrations of FCCP. Mitochondrial ROS production was measured by fluorometry using Amplex-Red. Pyridine dinucleotide levels were measured using HPLC. Before IR, increasing H+ leak decreased mitochondrial ROS production. After IR, ROS production was not affected by increasing H+ leak. H+ leak increased at end ischemia in control mitochondria. IPC mitochondria showed no change in the rate of H+ leak throughout IR. NADPH levels decreased after IR in both IPC and control mitochondria while NADH increased. Pharmacologically, increasing H+ leak is not a method of decreasing ROS production after IR. Replenishing the NADPH pool may be a means of scavenging the excess ROS thereby attenuating oxidative damage after IR.

Original languageEnglish (US)
Pages (from-to)H996-H1004
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume307
Issue number7
DOIs
StatePublished - Oct 1 2014
Externally publishedYes

Keywords

  • Ischemia-reperfusion
  • Mitochondria
  • Proton leak
  • Reactive oxygen species
  • Uncoupling

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine
  • Medicine(all)

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