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Published on: February 28, 2011
Mitochondrial oxygen tension within the heart.
Egbert G Mik1, Can Ince, Otto Eerbeek
1Department of Anesthesiology, ErasmusMC, University Medical Center Rotterdam, CE Rotterdam, The Netherlands. e.mik@erasmusmc.nl
Journal of Molecular and Cellular Cardiology
|February 24, 2009
Summary
This study reveals that heart mitochondria in vivo have higher oxygen levels than previously thought, with significant variations. Isolated Langendorff-perfused hearts show lower mitochondrial oxygen levels compared to working hearts.
Area of Science:
- Cardiac Physiology
- Mitochondrial Function
- Oxygen Transport
Background:
- Understanding mitochondrial oxygen tension (mitoPO2) is crucial for cardiac physiology.
- Previous studies lacked precise measurements of in vivo cardiac mitoPO2.
- The comparison between in vivo and isolated heart models remains unclear.
Purpose of the Study:
- To measure mitochondrial oxygenation (mitoPO2) in the intact, working heart in vivo.
- To determine the heterogeneity of mitoPO2 distribution within the heart.
- To compare cardiac mitoPO2 in vivo versus in isolated Langendorff-perfused hearts.
Main Methods:
- Development and validation of a novel optical technique for non-invasive mitoPO2 measurement.
- In vivo studies on intact hearts.
- Studies on isolated Langendorff-perfused rat hearts under varying conditions.
Main Results:
- In vivo mean mitoPO2 was 35±5 mm Hg, higher than often assumed.
- MitoPO2 distribution was highly heterogeneous, with significant fractions at low oxygen levels (0-20 mm Hg).
- Langendorff-perfused hearts exhibited lower mean mitoPO2 (29±5 mm Hg) and greater heterogeneity compared to in vivo hearts, except under maximal vasodilation.
Conclusions:
- In vivo cardiac mitoPO2 is higher and more heterogeneous than previously considered.
- The isolated Langendorff-perfused heart model does not fully replicate in vivo mitochondrial oxygenation.
- Mitochondrial oxygenation in the heart is a complex parameter influenced by physiological state and measurement model.
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