Synchronized Whole Cell Oscillations in Mitochondrial Metabolism Triggered by a Local Release of Reactive Oxygen Species in Cardiac Myocytes

Miguel A. Aon, Sonia Cortassa, Eduardo Marbán, Brian O'Rourke

Research output: Contribution to journalArticlepeer-review

Abstract

Reactive oxygen species (ROS) and/or Ca2+ overload can trigger depolarization of mitochondrial inner membrane potential (ΔΨ m) and cell injury. Little is known about how loss of ΔΨm in a small number of mitochondria might influence the overall function of the cell. Here we employ the narrow focal excitation volume of the two-photon microscope to examine the effect of local mitochondrial depolarization in guinea pig ventricular myocytes. Remarkably, a single local laser flash triggered synchronized and self-sustained oscillations in ΔΨm, NADH, and ROS after a delay of ∼40s, in more than 70% of the mitochondrial population. Oscillations were initiated only after a specific threshold level of mitochondrially produced ROS was exceeded, and did not involve the classical permeability transition pore or intracellular Ca 2+ overload. The synchronized transitions were abolished by several respiratory inhibitors or a superoxide dismutase mimetic. Anion channel inhibitors potentiated matrix ROS accumulation in the flashed region, but blocked propagation to the rest of the myocyte, suggesting that an inner membrane, superoxide-permeable, anion channel opens in response to free radicals. The transitions in mitochondrial energetics were tightly coupled to activation of sarcolemmal KATP currents, causing oscillations in action potential duration, and thus might contribute to catastrophic arrhythmias during ischemia-reperfusion injury.

Original languageEnglish (US)
Pages (from-to)44735-44744
Number of pages10
JournalJournal of Biological Chemistry
Volume278
Issue number45
DOIs
StatePublished - Nov 7 2003

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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