Cellular response to reperfused oxygen in the postischemic myocardium

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Abstract

Perfused rat heart experiments focused on determining the critical O2 level in postischemic myocardium. After a 20-min global ischemia, reperfusion began with O2-saturated saline buffer reflowing at different rates (0.5-12 ml/min). The 1H nuclear magnetic resonance (NMR) signal of the Val E11 myoglobin (Mb) gave an index of the intracellular oxygenation, whereas the 31P-NMR spectra reflected the high-energy phosphate and pH status. At the same time, physiological monitors recorded both contractile function and O2 consumption. Biochemical analysis determined the lactate concentration. Within 6-12 min of reperfusion, the O2 reached a new steady state, which depended directly on the flow rate. Below 12 ml/min reflow, the postischemic O2 level was consistently lower than the corresponding control values. Phosphocreatine, P(i), pH, myocardial O2 consumption, and lactate formation rate exhibited a similar linear relationship with MbO2 saturation in both the control and postischemic myocardium. It appears that neither the cellular energy production nor the steep intracellular O2 gradient has changed substantially in the postischemic myocardium.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume271
Issue number2 40-2
StatePublished - Aug 1996

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Myocardium
Oxygen
Reperfusion
Lactic Acid
Magnetic Resonance Spectroscopy
Phosphocreatine
Myoglobin
Buffers
Ischemia
Phosphates

Keywords

  • heart
  • ischemia
  • myoglobin
  • nuclear magnetic resonance
  • postischemia
  • stunned myocardium

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

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title = "Cellular response to reperfused oxygen in the postischemic myocardium",
abstract = "Perfused rat heart experiments focused on determining the critical O2 level in postischemic myocardium. After a 20-min global ischemia, reperfusion began with O2-saturated saline buffer reflowing at different rates (0.5-12 ml/min). The 1H nuclear magnetic resonance (NMR) signal of the Val E11 myoglobin (Mb) gave an index of the intracellular oxygenation, whereas the 31P-NMR spectra reflected the high-energy phosphate and pH status. At the same time, physiological monitors recorded both contractile function and O2 consumption. Biochemical analysis determined the lactate concentration. Within 6-12 min of reperfusion, the O2 reached a new steady state, which depended directly on the flow rate. Below 12 ml/min reflow, the postischemic O2 level was consistently lower than the corresponding control values. Phosphocreatine, P(i), pH, myocardial O2 consumption, and lactate formation rate exhibited a similar linear relationship with MbO2 saturation in both the control and postischemic myocardium. It appears that neither the cellular energy production nor the steep intracellular O2 gradient has changed substantially in the postischemic myocardium.",
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author = "Youngran Chung and Thomas Jue",
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KW - stunned myocardium

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