Myocardial oxygenation in vivo: Optical spectroscopy of cytoplasmic myoglobin and mitochondrial cytochromes

Andrew E. Arai, Claudia E. Kasserra, Paul Territo, Amir H. Gandjbakhche, Robert S. Balaban

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

The oxygenation state of myoglobin and the redox state of cytochrome c provide information on the PO2 in the cytosol and mitochondria, respectively. An optical 'window' from ~540 to 585 nm was found in the pig heart in vivo that permitted the monitoring of myoglobin and cytochrome c without interference from Hb oxygenation or blood volume. Scanning reflectance spectroscopy was performed on the surgically exposed left ventricle of pigs. Difference spectra between control and a total left anterior descending coronary artery occlusion revealed maxima and minima in this spectral region consistent with myoglobin deoxygenation and cytochrome c and b reduction. Comparison of in vivo data with in vitro fractions of the heart, including Hb-free tissue whole heart and homogenates, mitochondria, myoglobin, and pig red blood cells, reveals minimal contributions of Hb in vivo. This conclusion was confirmed by expanding the blood volume of the myocardium and increasing mean Hb O2 saturation with an intracoronary infusion of adenosine (20 μg · kg-1 · min-1), which had no significant effect on the 540- to 585-nm region. These results also suggested that myoglobin O2 saturation was not blood flow limited under these conditions in vivo. Work jump studies with phenylephrine also failed to change cytochrome c redox state or myoglobin oxygenation. Computer simulations using recent physical data are consistent with the notion that myoglobin O2 saturation is >92% under basal conditions and does not change significantly with moderate workloads. These studies show that reflectance spectroscopy can assess myocardial oxygenation in vivo. Myoglobin O2 saturation is very high and is not labile to moderate changes in cardiac workload in the open-chest pig model. These findings indicate that myoglobin does not contribute significantly to O2 transport via facilitated diffusion under these conditions.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume277
Issue number2 46-2
StatePublished - Aug 1999
Externally publishedYes

Fingerprint

Myoglobin
Cytochromes
Spectrum Analysis
Cytochromes c
Swine
Blood Volume
Workload
Oxidation-Reduction
Facilitated Diffusion
Heart Mitochondria
Cytochromes b
Coronary Occlusion
Phenylephrine
Computer Simulation
Cytosol
Adenosine
Heart Ventricles
Coronary Vessels
Myocardium
Mitochondria

Keywords

  • Computer simulation
  • Cytochrome b
  • Cytochrome c
  • Diffusion
  • Dog
  • Facilitated diffusion
  • Hemoglobin
  • Mitochondria
  • Oxygen
  • Oxygen consumption
  • Pig

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Myocardial oxygenation in vivo : Optical spectroscopy of cytoplasmic myoglobin and mitochondrial cytochromes. / Arai, Andrew E.; Kasserra, Claudia E.; Territo, Paul; Gandjbakhche, Amir H.; Balaban, Robert S.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 277, No. 2 46-2, 08.1999.

Research output: Contribution to journalArticle

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