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Spin label oximetry to assess extracellular oxygen during myocardial ischemia. Free Radic Biol Med 1997;22(1-2):109-15

Date

01/01/1997

Pubmed ID

8958135

DOI

10.1016/s0891-5849(96)00289-4

Scopus ID

2-s2.0-0029911540   22 Citations

Abstract

We describe real-time measurement of myocardial oxygen consumption during ischemia in the intact heart. Measurement of extracellular oxygen concentration during myocardial ischemia by spin label oximetry has been limited by ischemia-induced reduction of the neutral, water-soluble nitroxide TEMPONE. We have overcome this problem by encapsulating the nitroxides. Isolated immature (7-10 d old) rabbit hearts (n = 8) were perfused aerobically within the cavity of a loop gap resonator with bicarbonate buffer containing an oxygen-sensitive, lipid-soluble nitroxide (14N-TEMPO laurate in FC-43 perfluorocarbon micelles) and a much less oxygen-sensitive and positively charged nitroxide (15N-TEMPO choline in multilamellar vesicles) as an internal standard. The ratio of the ESR signal amplitudes of these nitroxides was used as a sensitive index of oxygen concentration. Sequestration of the nitroxides decreased their reduction rate by ascorbate in comparison with nonsequestered nitroxides. Hearts were subjected to 60 min of global no-flow ischemia at 20 degrees C. Extracellular oxygen content (mean +/- SD) during aerobic perfusion was 1195 +/- 55 mumol/liter. The electron spin resonance signal from TEMPO laurate increased with the onset and progression of ischemia, consistent with a decrease in extracellular oxygen, while the signal for TEMPO choline was relatively unchanged. Extracellular oxygen content after 40 and 60 min of ischemia was reduced to 393 +/- 27 mumol/liter (p < .05) and 61 +/- 5 mumol/liter (p < .05), respectively. We conclude that spin-label oximetry can directly and precisely measure myocardial oxygen consumption at constant temperature during ischemia in the intact heart.

Author List

Baker JE, Froncisz W, Joseph J, Kalyanaraman B

Authors

John E. Baker PhD Professor in the Surgery department at Medical College of Wisconsin
Balaraman Kalyanaraman PhD Chair, Professor in the Biophysics department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Electron Spin Resonance Spectroscopy
Feasibility Studies
Free Radicals
In Vitro Techniques
Liposomes
Micelles
Myocardial Ischemia
Nitrogen Oxides
Oxidation-Reduction
Oximetry
Oxygen
Perfusion
Rabbits
Spin Labels
Triacetoneamine-N-Oxyl
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a