Myocardial oxygen demand and redox state affect fatty acid oxidation in the potassium-arrested heart

Matthias Peltz, Tian Teng He, Glenn A. Adams IV, Robert Y. Chao, Michael E Jessen

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Background Fatty acid (FA) metabolism is suppressed under conditions of cardioplegic arrest, but the mechanism behind this effect is unknown. We hypothesized that alterations in redox state and oxygen demand control myocardial FA utilization during potassium arrest. Methods Rat hearts were perfused with Krebs-Heinseleit buffer containing physiologic concentrations of FAs, ketones, and carbohydrates with unique 13Carbon labeling patterns. Cytosolic and mitochondrial redox states were altered by manipulating the lactate/pyruvate and ketone redox couples, respectively. Myocardial oxygen consumption was increased by adding the mitochondrial uncoupler 2,4-dinitrophenol to the perfusate. Experiments were conducted under conditions of normokalemic perfusion and potassium cardioplegia (PC). Substrate oxidation rates were derived from 13Carbon isotopomer data and myocardial oxygen consumption. Results Continuous perfusion under conditions of potassium arrest dramatically reduced fatty acid oxidation. Both the addition of 2,4-dinitrophenol and alteration of mitochondrial redox state significantly increased FA oxidation during PC. In contrast to normokalemic perfusion, altering cytosolic redox state during PC did not change FA oxidation. Conclusions These data suggest that mitochondrial redox state and oxygen demand are important determinants of myocardial FA oxidation during potassium arrest. FA oxidation appears to be regulated by different factors during PC than normokalemic perfusion.

Original languageEnglish (US)
Pages (from-to)150-159
Number of pages10
JournalSurgery
Volume136
Issue number2
DOIs
StatePublished - Aug 2004

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Oxidation-Reduction
Potassium
Fatty Acids
Induced Heart Arrest
Oxygen
Perfusion
2,4-Dinitrophenol
Ketones
Oxygen Consumption
Pyruvic Acid
Lactic Acid
Buffers
Carbohydrates

ASJC Scopus subject areas

  • Surgery

Cite this

Myocardial oxygen demand and redox state affect fatty acid oxidation in the potassium-arrested heart. / Peltz, Matthias; He, Tian Teng; Adams IV, Glenn A.; Chao, Robert Y.; Jessen, Michael E.

In: Surgery, Vol. 136, No. 2, 08.2004, p. 150-159.

Research output: Contribution to journalArticle

Peltz, Matthias ; He, Tian Teng ; Adams IV, Glenn A. ; Chao, Robert Y. ; Jessen, Michael E. / Myocardial oxygen demand and redox state affect fatty acid oxidation in the potassium-arrested heart. In: Surgery. 2004 ; Vol. 136, No. 2. pp. 150-159.
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AB - Background Fatty acid (FA) metabolism is suppressed under conditions of cardioplegic arrest, but the mechanism behind this effect is unknown. We hypothesized that alterations in redox state and oxygen demand control myocardial FA utilization during potassium arrest. Methods Rat hearts were perfused with Krebs-Heinseleit buffer containing physiologic concentrations of FAs, ketones, and carbohydrates with unique 13Carbon labeling patterns. Cytosolic and mitochondrial redox states were altered by manipulating the lactate/pyruvate and ketone redox couples, respectively. Myocardial oxygen consumption was increased by adding the mitochondrial uncoupler 2,4-dinitrophenol to the perfusate. Experiments were conducted under conditions of normokalemic perfusion and potassium cardioplegia (PC). Substrate oxidation rates were derived from 13Carbon isotopomer data and myocardial oxygen consumption. Results Continuous perfusion under conditions of potassium arrest dramatically reduced fatty acid oxidation. Both the addition of 2,4-dinitrophenol and alteration of mitochondrial redox state significantly increased FA oxidation during PC. In contrast to normokalemic perfusion, altering cytosolic redox state during PC did not change FA oxidation. Conclusions These data suggest that mitochondrial redox state and oxygen demand are important determinants of myocardial FA oxidation during potassium arrest. FA oxidation appears to be regulated by different factors during PC than normokalemic perfusion.

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