Hibernation during hypoxia in cardiomyocytes. Role of mitochondria as the O2 sensor

G. R Scott Budinger, Jacques Duranteau, Navdeep S. Chandel, Paul T. Schumacker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

131 Scopus citations

Abstract

During myocardial hibernation, decreases in coronary perfusion elicit inhibition of contraction, suggesting that energy demand is attenuated. We previously found an inhibition of contraction and O2 consumption during hypoxia (3% O2; PO2 = 20 torr for >2 h) in cardiomyocytes, which was reversible after reoxygenation. This study sought to determine whether mitochondria function as cellular O2 sensors mediating this response. Embryonic cardiomyocytes were studied under controlled O2 conditions. Hypoxia produced no acute decrease in mitochondrial potential as assessed using tetramethylrhodamine ethylester (TMRE). Cellular [ATP] was preserved throughout hypoxia, as assessed using the probe Magnesium Green. Thus, ATP synthesis and utilization remained closely coupled. Cells adapted to hypoxia for >2 h exhibited a 4% increase in mitochondrial potential upon reoxygenation, suggesting that a partial inhibition of cytochrome c oxidase had existed. To test whether the oxidase serves as an O2 sensor, azide was administered (1 mM) to simulate the effects of hypoxia by lowering the V(max) of the oxidase. The effects of azide on contraction and mitochondrial potential mimicked the response to hypoxia. We conclude that partial inhibition of cytochrome oxidase during hypoxia allows mitochondria to function as the O2 sensor mediating the decreases in ATP utilization and O2 consumption during hypoxia.

Original languageEnglish (US)
Pages (from-to)3320-3326
Number of pages7
JournalJournal of Biological Chemistry
Volume273
Issue number6
DOIs
StatePublished - Feb 6 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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