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Flam E, Jang C, Murashige D, Yang Y, Morley MP, Jung S, Kantner DS, Pepper H, Bedi KC, Brandimarto J, Prosser BL, Cappola T, Snyder NW, Rabinowitz JD, Margulies KB, Arany Z. Integrated landscape of cardiac metabolism in end-stage human nonischemic dilated cardiomyopathy. NATURE CARDIOVASCULAR RESEARCH 2022; 1:817-829. [PMID: 36776621 PMCID: PMC9910091 DOI: 10.1038/s44161-022-00117-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 07/08/2022] [Indexed: 01/03/2023]
Abstract
Heart failure (HF) is a leading cause of mortality. Failing hearts undergo profound metabolic changes, but a comprehensive evaluation in humans is lacking. We integrate plasma and cardiac tissue metabolomics of 678 metabolites, genome-wide RNA-sequencing, and proteomic studies to examine metabolic status in 87 explanted human hearts from 39 patients with end-stage HF compared with 48 nonfailing donors. We confirm bioenergetic defects in human HF and reveal selective depletion of adenylate purines required for maintaining ATP levels. We observe substantial reductions in fatty acids and acylcarnitines in failing tissue, despite plasma elevations, suggesting defective import of fatty acids into cardiomyocytes. Glucose levels, in contrast, are elevated. Pyruvate dehydrogenase, which gates carbohydrate oxidation, is de-repressed, allowing increased lactate and pyruvate burning. Tricarboxylic acid cycle intermediates are significantly reduced. Finally, bioactive lipids are profoundly reprogrammed, with marked reductions in ceramides and elevations in lysoglycerophospholipids. These data unveil profound metabolic abnormalities in human failing hearts.
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Affiliation(s)
- Emily Flam
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Cholsoon Jang
- Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Department of Biological Chemistry, University of California Irvine, Irvine, CA, USA
| | - Danielle Murashige
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Yifan Yang
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael P. Morley
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Sunhee Jung
- Department of Biological Chemistry, University of California Irvine, Irvine, CA, USA
| | - Daniel S. Kantner
- Center for Metabolic Disease Research, Department of Cardiovascular Science, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Hannah Pepper
- Center for Metabolic Disease Research, Department of Cardiovascular Science, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Kenneth C. Bedi
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Jeff Brandimarto
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Benjamin L. Prosser
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
- Department of Physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Thomas Cappola
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Nathaniel W. Snyder
- Center for Metabolic Disease Research, Department of Cardiovascular Science, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Joshua D. Rabinowitz
- Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Kenneth B. Margulies
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
| | - Zolt Arany
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA, USA
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2
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Lindsay RT, Dieckmann S, Krzyzanska D, Manetta-Jones D, West JA, Castro C, Griffin JL, Murray AJ. β-hydroxybutyrate accumulates in the rat heart during low-flow ischaemia with implications for functional recovery. eLife 2021; 10:e71270. [PMID: 34491199 PMCID: PMC8423437 DOI: 10.7554/elife.71270] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/23/2021] [Indexed: 12/15/2022] Open
Abstract
Extrahepatic tissues which oxidise ketone bodies also have the capacity to accumulate them under particular conditions. We hypothesised that acetyl-coenzyme A (acetyl-CoA) accumulation and altered redox status during low-flow ischaemia would support ketone body production in the heart. Combining a Langendorff heart model of low-flow ischaemia/reperfusion with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS), we show that β-hydroxybutyrate (β-OHB) accumulated in the ischaemic heart to 23.9 nmol/gww and was secreted into the coronary effluent. Sodium oxamate, a lactate dehydrogenase (LDH) inhibitor, increased ischaemic β-OHB levels 5.3-fold and slowed contractile recovery. Inhibition of β-hydroxy-β-methylglutaryl (HMG)-CoA synthase (HMGCS2) with hymeglusin lowered ischaemic β-OHB accumulation by 40%, despite increased flux through succinyl-CoA-3-oxaloacid CoA transferase (SCOT), resulting in greater contractile recovery. Hymeglusin also protected cardiac mitochondrial respiratory capacity during ischaemia/reperfusion. In conclusion, net ketone generation occurs in the heart under conditions of low-flow ischaemia. The process is driven by flux through both HMGCS2 and SCOT, and impacts on cardiac functional recovery from ischaemia/reperfusion.
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Affiliation(s)
- Ross T Lindsay
- Department of Physiology, Development and Neuroscience, University of CambridgeLondonUnited Kingdom
- Department of Biochemistry and Cambridge Systems Biology Centre, University of CambridgeLondonUnited Kingdom
| | - Sophie Dieckmann
- Department of Physiology, Development and Neuroscience, University of CambridgeLondonUnited Kingdom
| | - Dominika Krzyzanska
- Department of Physiology, Development and Neuroscience, University of CambridgeLondonUnited Kingdom
| | - Dominic Manetta-Jones
- Department of Physiology, Development and Neuroscience, University of CambridgeLondonUnited Kingdom
| | - James A West
- Department of Biochemistry and Cambridge Systems Biology Centre, University of CambridgeLondonUnited Kingdom
| | - Cecilia Castro
- Department of Biochemistry and Cambridge Systems Biology Centre, University of CambridgeLondonUnited Kingdom
| | - Julian L Griffin
- Department of Biochemistry and Cambridge Systems Biology Centre, University of CambridgeLondonUnited Kingdom
- Section of Biomolecular Medicine, Systems Medicine, Department of Metabolism, Digestion and Reproduction, Imperial College LondonLondonUnited Kingdom
| | - Andrew J Murray
- Department of Physiology, Development and Neuroscience, University of CambridgeLondonUnited Kingdom
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3
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Zhang Y, Taufalele PV, Cochran JD, Robillard-Frayne I, Marx JM, Soto J, Rauckhorst AJ, Tayyari F, Pewa AD, Gray LR, Teesch LM, Puchalska P, Funari TR, McGlauflin R, Zimmerman K, Kutschke WJ, Cassier T, Hitchcock S, Lin K, Kato KM, Stueve JL, Haff L, Weiss RM, Cox JE, Rutter J, Taylor EB, Crawford PA, Lewandowski ED, Des Rosiers C, Abel ED. Mitochondrial pyruvate carriers are required for myocardial stress adaptation. Nat Metab 2020; 2:1248-1264. [PMID: 33106689 PMCID: PMC8015649 DOI: 10.1038/s42255-020-00288-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 09/03/2020] [Indexed: 12/20/2022]
Abstract
In addition to fatty acids, glucose and lactate are important myocardial substrates under physiologic and stress conditions. They are metabolized to pyruvate, which enters mitochondria via the mitochondrial pyruvate carrier (MPC) for citric acid cycle metabolism. In the present study, we show that MPC-mediated mitochondrial pyruvate utilization is essential for the partitioning of glucose-derived cytosolic metabolic intermediates, which modulate myocardial stress adaptation. Mice with cardiomyocyte-restricted deletion of subunit 1 of MPC (cMPC1-/-) developed age-dependent pathologic cardiac hypertrophy, transitioning to a dilated cardiomyopathy and premature death. Hypertrophied hearts accumulated lactate, pyruvate and glycogen, and displayed increased protein O-linked N-acetylglucosamine, which was prevented by increasing availability of non-glucose substrates in vivo by a ketogenic diet (KD) or a high-fat diet, which reversed the structural, metabolic and functional remodelling of non-stressed cMPC1-/- hearts. Although concurrent short-term KDs did not rescue cMPC1-/- hearts from rapid decompensation and early mortality after pressure overload, 3 weeks of a KD before transverse aortic constriction was sufficient to rescue this phenotype. Together, our results highlight the centrality of pyruvate metabolism to myocardial metabolism and function.
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MESH Headings
- Adaptation, Physiological/genetics
- Adaptation, Physiological/physiology
- Animals
- Anion Transport Proteins/genetics
- Anion Transport Proteins/metabolism
- Cardiomegaly/diagnostic imaging
- Cardiomegaly/genetics
- Cardiomegaly/metabolism
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/metabolism
- Constriction, Pathologic
- Cytosol/metabolism
- Diet, High-Fat
- Diet, Ketogenic
- Echocardiography
- In Vitro Techniques
- Mice
- Mice, Knockout
- Mitochondria, Heart/metabolism
- Mitochondrial Membrane Transport Proteins/genetics
- Mitochondrial Membrane Transport Proteins/metabolism
- Myocardium/metabolism
- Myocytes, Cardiac/metabolism
- Pyruvic Acid/metabolism
- Stress, Physiological/genetics
- Stress, Physiological/physiology
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Affiliation(s)
- Yuan Zhang
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Division of Endocrinology and Metabolism, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Paul V Taufalele
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Jesse D Cochran
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | | | - Jonas Maximilian Marx
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL, USA
- Friedrich-Schiller University of Jena, Jena, Germany
| | - Jamie Soto
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Mouse Metabolic Phenotyping Core, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Adam J Rauckhorst
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Fariba Tayyari
- Metabolomics Core Facility, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Alvin D Pewa
- Metabolomics Core Facility, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Lawrence R Gray
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Lynn M Teesch
- Metabolomics Core Facility, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Patrycja Puchalska
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL, USA
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Trevor R Funari
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Rose McGlauflin
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Kathy Zimmerman
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - William J Kutschke
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Thomas Cassier
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Shannon Hitchcock
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Kevin Lin
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Kevin M Kato
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Jennifer L Stueve
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Lauren Haff
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Robert M Weiss
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - James E Cox
- Department of Biochemistry, School of Medicine, University of Utah, Salt Lake City, UT, USA
- Metabolomics Core Research Facility, School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Jared Rutter
- Department of Biochemistry, School of Medicine, University of Utah, Salt Lake City, UT, USA
- Howard Hughes Medical Institute, School of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Eric B Taylor
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Metabolomics Core Facility, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Peter A Crawford
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL, USA
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - E Douglas Lewandowski
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL, USA
- Department of Internal Medicine and Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Christine Des Rosiers
- Department of Nutrition, Université de Montréal and Montreal Heart Institute, Montreal, Canada
| | - E Dale Abel
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
- Division of Endocrinology and Metabolism, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
- Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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4
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Murashige D, Jang C, Neinast M, Edwards JJ, Cowan A, Hyman MC, Rabinowitz JD, Frankel DS, Arany Z. Comprehensive quantification of fuel use by the failing and nonfailing human heart. Science 2020; 370:364-368. [PMID: 33060364 PMCID: PMC7871704 DOI: 10.1126/science.abc8861] [Citation(s) in RCA: 267] [Impact Index Per Article: 66.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/25/2020] [Indexed: 12/21/2022]
Abstract
The heart consumes circulating nutrients to fuel lifelong contraction, but a comprehensive mapping of human cardiac fuel use is lacking. We used metabolomics on blood from artery, coronary sinus, and femoral vein in 110 patients with or without heart failure to quantify the uptake and release of 277 metabolites, including all major nutrients, by the human heart and leg. The heart primarily consumed fatty acids and, unexpectedly, little glucose; secreted glutamine and other nitrogen-rich amino acids, indicating active protein breakdown, at a rate ~10 times that of the leg; and released intermediates of the tricarboxylic acid cycle, balancing anaplerosis from amino acid breakdown. Both heart and leg consumed ketones, glutamate, and acetate in direct proportionality to circulating levels, indicating that availability is a key driver for consumption of these substrates. The failing heart consumed more ketones and lactate and had higher rates of proteolysis. These data provide a comprehensive and quantitative picture of human cardiac fuel use.
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Affiliation(s)
- Danielle Murashige
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Cholsoon Jang
- Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Michael Neinast
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jonathan J Edwards
- Department of Pediatrics, Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Alexis Cowan
- Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Matthew C Hyman
- Division of Cardiovascular Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Joshua D Rabinowitz
- Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - David S Frankel
- Division of Cardiovascular Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Zolt Arany
- Perelman School of Medicine, Cardiovascular Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
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5
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Tsogtbaatar E, Cocuron JC, Alonso AP. Non-conventional pathways enable pennycress (Thlaspi arvense L.) embryos to achieve high efficiency of oil biosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3037-3051. [PMID: 32006014 PMCID: PMC7260723 DOI: 10.1093/jxb/eraa060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 02/03/2020] [Indexed: 05/22/2023]
Abstract
Pennycress (Thlaspi arvense L.) accumulates oil up to 35% of the total seed biomass, and its overall fatty acid composition is suitable for aviation fuel. However, for this plant to become economically viable, its oil production needs to be improved. In vivo culture conditions that resemble the development of pennycress embryos in planta were developed based on the composition of the liquid endosperm. Then, substrate uptake rates and biomass accumulation were measured from cultured pennycress embryos, revealing a biosynthetic efficiency of 93%, which is one of the highest in comparison with other oilseeds to date. Additionally, the ratio of carbon in oil to CO2 indicated that non-conventional pathways are likely to be responsible for such a high carbon conversion efficiency. To identify the reactions enabling this phenomenon, parallel labeling experiments with 13C-labeled substrates were conducted in pennycress embryos. The main findings of these labeling experiments include: (i) the occurrence of the oxidative reactions of the pentose phosphate pathway in the cytosol; (ii) the reversibility of isocitrate dehydrogenase; (iii) the operation of the plastidic NADP-dependent malic enzyme; and (iv) the refixation of CO2 by Rubisco. These reactions are key providers of carbon and reductant for fatty acid synthesis and elongation.
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Affiliation(s)
| | | | - Ana Paula Alonso
- BioDiscovery Institute, University of North Texas, Denton, TX, USA
- Department of Biological Sciences, University of North Texas, Denton, TX, USA
- Correspondence:
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6
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Kajimoto M, Nuri M, Isern NG, Robillard-Frayne I, Des Rosiers C, Portman MA. Metabolic Response to Stress by the Immature Right Ventricle Exposed to Chronic Pressure Overload. J Am Heart Assoc 2019; 8:e013169. [PMID: 31450994 PMCID: PMC6755848 DOI: 10.1161/jaha.119.013169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Background The right ventricle exposed to chronic pressure overload exhibits hypertrophy and decompensates when exposed to stress. We hypothesize that impaired ability to increase myocardial oxidative flux through pyruvate dehydrogenase leads to hypertrophied right ventricular (RV) dysfunction when exposed to hemodynamic stress, and pyruvate dehydrogenase stimulation can improve RV function. Methods and Results Infant male Yorkshire piglets (13.5±0.6 kg weight, n=19) were used to assess substrate fractional contribution to the citric acid cycle after sustained pulmonary artery banding (PAB). Carbon 13–labeled glucose, lactate, and leucine, oxidative substrate tracers for the citric acid cycle, were infused into the right coronary artery on 7 to 10 days after PAB. RV systolic pressure, RV free wall thickness, and individual cardiomyocyte cell size after PAB were significantly elevated compared with the sham group. Both fractional glucose and lactate oxidations in the PAB group were >2‐fold higher than in the sham group. Pigs with overdrive atrial pacing (≈80% increase in heart rate) stress after PAB showed only a 22% increase in rate‐pressure product from baseline before atrial pacing and limited carbohydrate oxidation rate in the right ventricle. Intracoronary infusion of dichloroacetate, a pyruvate dehydrogenase agonist, produced higher rate‐pressure product (59% increase) in response to increased workload by atrial pacing in association with a marked increase in lactate oxidation. Conclusions The immature hypertrophied right ventricle shows limited ability to increase carbohydrate oxidation in response to tachycardia stress leading to energy supply/utilization imbalance and decreased systolic function. Enhanced pyruvate dehydrogenase activation by dichloroacetate increases energy supply and preserves hypertrophied RV contractile function during hemodynamic stress.
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Affiliation(s)
- Masaki Kajimoto
- Center for Integrative Brain Research Seattle Children's Research Institute Seattle WA
| | - Muhammad Nuri
- Center for Integrative Brain Research Seattle Children's Research Institute Seattle WA.,Division of Pediatric Cardiac Surgery Seattle Children's Hospital Seattle WA
| | - Nancy G Isern
- Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratories Richland WA
| | | | - Christine Des Rosiers
- Department of Nutrition Université de Montréal and Montreal Heart Institute Montréal Quebec Canada
| | - Michael A Portman
- Center for Integrative Brain Research Seattle Children's Research Institute Seattle WA.,Division of Cardiology Department of Pediatrics University of Washington Seattle WA
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7
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Kajimoto M, Ledee DR, Olson AK, Isern NG, Robillard-Frayne I, Des Rosiers C, Portman MA. Selective cerebral perfusion prevents abnormalities in glutamate cycling and neuronal apoptosis in a model of infant deep hypothermic circulatory arrest and reperfusion. J Cereb Blood Flow Metab 2016; 36:1992-2004. [PMID: 27604310 PMCID: PMC5094314 DOI: 10.1177/0271678x16666846] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 07/27/2016] [Indexed: 12/22/2022]
Abstract
Deep hypothermic circulatory arrest is often required for the repair of complex congenital cardiac defects in infants. However, deep hypothermic circulatory arrest induces neuroapoptosis associated with later development of neurocognitive abnormalities. Selective cerebral perfusion theoretically provides superior neural protection possibly through modifications in cerebral substrate oxidation and closely integrated glutamate cycling. We tested the hypothesis that selective cerebral perfusion modulates glucose utilization, and ameliorates abnormalities in glutamate flux, which occur in association with neuroapoptosis during deep hypothermic circulatory arrest. Eighteen infant male Yorkshire piglets were assigned randomly to two groups of seven (deep hypothermic circulatory arrest or deep hypothermic circulatory arrest with selective cerebral perfusion for 60 minutes at 18℃) and four control pigs without cardiopulmonary bypass support. Carbon-13-labeled glucose as a metabolic tracer was infused, and gas chromatography-mass spectrometry and nuclear magnetic resonance were used for metabolic analysis in the frontal cortex. Following 2.5 h of cerebral reperfusion, we observed similar cerebral adenosine triphosphate levels, absolute levels of lactate and citric acid cycle intermediates, and carbon-13 enrichment among three groups. However, deep hypothermic circulatory arrest induced significant abnormalities in glutamate cycling resulting in reduced glutamate/glutamine and elevated γ-aminobutyric acid/glutamate along with neuroapoptosis, which were all prevented by selective cerebral perfusion. The data suggest that selective cerebral perfusion prevents these modifications in glutamate/glutamine/γ-aminobutyric acid cycling and protects the cerebral cortex from apoptosis.
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Affiliation(s)
- Masaki Kajimoto
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA, USA
| | - Dolena R Ledee
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA, USA
| | - Aaron K Olson
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA, USA.,Division of Cardiology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Nancy G Isern
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratories, Richland, WA, USA
| | | | - Christine Des Rosiers
- Department of Nutrition, Université de Montréal and Montreal Heart Institute, Montréal, QC, Canada
| | - Michael A Portman
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA, USA .,Division of Cardiology, Department of Pediatrics, University of Washington, Seattle, WA, USA
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8
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Crown SB, Kelleher JK, Rouf R, Muoio DM, Antoniewicz MR. Comprehensive metabolic modeling of multiple 13C-isotopomer data sets to study metabolism in perfused working hearts. Am J Physiol Heart Circ Physiol 2016; 311:H881-H891. [PMID: 27496880 DOI: 10.1152/ajpheart.00428.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 07/25/2016] [Indexed: 11/22/2022]
Abstract
In many forms of cardiomyopathy, alterations in energy substrate metabolism play a key role in disease pathogenesis. Stable isotope tracing in rodent heart perfusion systems can be used to determine cardiac metabolic fluxes, namely those relative fluxes that contribute to pyruvate, the acetyl-CoA pool, and pyruvate anaplerosis, which are critical to cardiac homeostasis. Methods have previously been developed to interrogate these relative fluxes using isotopomer enrichments of measured metabolites and algebraic equations to determine a predefined metabolic flux model. However, this approach is exquisitely sensitive to measurement error, thus precluding accurate relative flux parameter determination. In this study, we applied a novel mathematical approach to determine relative cardiac metabolic fluxes using 13C-metabolic flux analysis (13C-MFA) aided by multiple tracer experiments and integrated data analysis. Using 13C-MFA, we validated a metabolic network model to explain myocardial energy substrate metabolism. Four different 13C-labeled substrates were queried (i.e., glucose, lactate, pyruvate, and oleate) based on a previously published study. We integrated the analysis of the complete set of isotopomer data gathered from these mouse heart perfusion experiments into a single comprehensive network model that delineates substrate contributions to both pyruvate and acetyl-CoA pools at a greater resolution than that offered by traditional methods using algebraic equations. To our knowledge, this is the first rigorous application of 13C-MFA to interrogate data from multiple tracer experiments in the perfused heart. We anticipate that this approach can be used widely to study energy substrate metabolism in this and other similar biological systems.
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Affiliation(s)
- Scott B Crown
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University, Durham, North Carolina;
| | - Joanne K Kelleher
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Rosanne Rouf
- Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Deborah M Muoio
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology Institute, Duke University, Durham, North Carolina; Department of Medicine, Duke University, Durham, North Carolina; Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina; and
| | - Maciek R Antoniewicz
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delware
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9
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Ruiz M, Gélinas R, Vaillant F, Lauzier B, Des Rosiers C. Metabolic Tracing Using Stable Isotope-Labeled Substrates and Mass Spectrometry in the Perfused Mouse Heart. Methods Enzymol 2015; 561:107-47. [PMID: 26358903 DOI: 10.1016/bs.mie.2015.06.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There has been a resurgence of interest for the field of cardiac metabolism catalyzed by evidence demonstrating a role of metabolic dysregulation in the pathogenesis of heart disease as well as the increased need for new therapeutic targets for patients with these diseases. In this regard, measuring substrate fluxes is critical in providing insight into the dynamics of cellular metabolism and in delineating the regulation of metabolite production and utilization. This chapter provides a comprehensive description of concepts, guidelines, and tips to assess metabolic fluxes relevant to energy substrate metabolism using (13)C-labeled substrates and (13)C-isotopomer analysis by gas chromatography-mass spectrometry (GC-MS), and the ex vivo working heart as study model. The focus will be on the mouse and on flux parameters, which are commonly assessed in the field, namely, those relevant to substrate selection for energy metabolism, specifically the relative contribution of carbohydrate (glucose, lactate, and pyruvate) and fatty acid oxidation to acetyl-CoA formation for citrate synthesis, glycolysis, as well as anaplerosis. We provide detailed procedures for the heart isolation and perfusion in the working mode as well as for sample processing for metabolite extraction and analysis by GC-MS and subsequent data processing for calculation of metabolic flux parameters. Finally, we address practical considerations and discuss additional applications and future challenges.
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Affiliation(s)
- Matthieu Ruiz
- Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada; Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada
| | - Roselle Gélinas
- Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Fanny Vaillant
- IHU Institut de Rythmologie et Modélisation Cardiaque, Fondation Bordeaux, Université de Bordeaux, Bordeaux, France; Inserm U1045 Centre de Recherche Cardio-Thoracique de Bordeaux, Université de Bordeaux, Bordeaux, France
| | | | - Christine Des Rosiers
- Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada; Montreal Heart Institute, Université de Montréal, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montreal, Quebec, Canada.
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10
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Gurji HA, White DW, Hoxha B, Sun J, Harbor JP, Schulz DR, Williams AG, Olivencia-Yurvati AH, Mallet RT. Pyruvate-enriched resuscitation: metabolic support of post-ischemic hindlimb muscle in hypovolemic goats. Exp Biol Med (Maywood) 2014; 239:240-9. [PMID: 24414481 DOI: 10.1177/1535370213514329] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Tourniquet-imposed ischemia-reperfusion of extremities generates reactive oxygen and nitrogen species (RONS), which can disrupt intermediary metabolism and ATP production. This study tested the hypothesis that fluid resuscitation with pyruvate, a natural antioxidant and metabolic fuel, ameliorates the deleterious effects of ischemia-reperfusion on intermediary metabolism in skeletal muscle. Anesthetized male goats (∼25 kg) were bled to a mean arterial pressure of 48 ± 1 mmHg and then subjected to 90 min hindlimb ischemia with a tourniquet and femoral crossclamp, followed by 4-h reperfusion. Lactated Ringers (LR) or pyruvate Ringers (PR) was infused intravenous for 90 min, from 30 min ischemia to 30 min reperfusion, to deliver 0.05 mmol kg(-1) min(-1) lactate or pyruvate. Time controls (TC) underwent neither hemorrhage nor hindlimb ischemia. Lipid peroxidation product 8-isoprostane, RONS-sensitive aconitase and creatine kinase activities, antioxidant superoxide dismutase activity, and phosphocreatine phosphorylation potential ([PCr]/[{Cr}{P(i)}]), an index of tissue energy state, were measured in reperfused gastrocnemius at 90 min resuscitation (n = 6 all groups) and 3.5 h post-resuscitation (n = 8 TC, 9 LR, 10 PR). PR more effectively than LR suppressed 8-isoprostane formation, prevented inactivation of aconitase and creatine kinase, doubled superoxide dismutase activity, and augmented [PCr]/([Cr][P(i)]). Pyruvate-enriched Ringer's is metabolically superior to Ringer's lactate for fluid resuscitation of tourniqueted muscle.
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Affiliation(s)
- Hunaid A Gurji
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA
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11
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Parallel labeling experiments and metabolic flux analysis: Past, present and future methodologies. Metab Eng 2012; 16:21-32. [PMID: 23246523 DOI: 10.1016/j.ymben.2012.11.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 11/09/2012] [Accepted: 11/21/2012] [Indexed: 01/22/2023]
Abstract
Radioactive and stable isotopes have been applied for decades to elucidate metabolic pathways and quantify carbon flow in cellular systems using mass and isotope balancing approaches. Isotope-labeling experiments can be conducted as a single tracer experiment, or as parallel labeling experiments. In the latter case, several experiments are performed under identical conditions except for the choice of substrate labeling. In this review, we highlight robust approaches for probing metabolism and addressing metabolically related questions though parallel labeling experiments. In the first part, we provide a brief historical perspective on parallel labeling experiments, from the early metabolic studies when radioisotopes were predominant to present-day applications based on stable-isotopes. We also elaborate on important technical and theoretical advances that have facilitated the transition from radioisotopes to stable-isotopes. In the second part of the review, we focus on parallel labeling experiments for (13)C-metabolic flux analysis ((13)C-MFA). Parallel experiments offer several advantages that include: tailoring experiments to resolve specific fluxes with high precision; reducing the length of labeling experiments by introducing multiple entry-points of isotopes; validating biochemical network models; and improving the performance of (13)C-MFA in systems where the number of measurements is limited. We conclude by discussing some challenges facing the use of parallel labeling experiments for (13)C-MFA and highlight the need to address issues related to biological variability, data integration, and rational tracer selection.
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12
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Lauzier B, Vaillant F, Merlen C, Gélinas R, Bouchard B, Rivard ME, Labarthe F, Dolinsky VW, Dyck JRB, Allen BG, Chatham JC, Des Rosiers C. Metabolic effects of glutamine on the heart: anaplerosis versus the hexosamine biosynthetic pathway. J Mol Cell Cardiol 2012. [PMID: 23201305 DOI: 10.1016/j.yjmcc.2012.11.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Glutamine, the most abundant amino acid in plasma, has attracted considerable interest for its cardioprotective properties. The primary effect of glutamine in the heart is commonly believed to be mediated via its anaplerotic metabolism to citric acid cycle (CAC) intermediates; however, there is little direct evidence to support this concept. Another potential candidate is the hexosamine biosynthetic pathway (HBP), which has recently been shown to modulate cardiomyocyte function and metabolism. Therefore, the goal of this study was to evaluate the contribution of anaplerosis and the HBP to the acute metabolic effects of glutamine in the heart. Normoxic ex vivo working rat hearts were perfused with (13)C-labeled substrates to assess relevant metabolic fluxes either with a physiological mixture of carbohydrates and a fatty acid (control) or under conditions of restricted pyruvate anaplerosis. Addition of a physiological concentration of glutamine (0.5mM) had no effect on contractile function of hearts perfused under the control condition, but improved that of hearts perfused under restricted pyruvate anaplerosis. Changes in CAC intermediate concentrations as well as (13)C-enrichment from [U-(13)C]glutamine did not support a major role of glutamine anaplerosis under any conditions. Under the control condition, however, glutamine significantly increased the contribution of exogenous oleate to β-oxidation, 1.6-fold, and triglyceride formation, 2.8-fold. Glutamine had no effect on malonyl-CoA or AMP kinase activity levels; however, it resulted in a higher plasma membrane level of the fatty acid transporter CD36. These metabolic effects of glutamine were reversed by azaserine, which inhibits glucose entry into the HPB. Our results reveal a metabolic role of physiological concentration of glutamine in the healthy working heart beyond anaplerosis. This role appears to involve the HBP and regulation of fatty acid entry and metabolism via CD36. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism".
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Affiliation(s)
- Benjamin Lauzier
- Montreal Heart Institute and Department of Nutrition and Medicine, Université de Montréal, Canada H1T 1C8
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13
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Filipp FV, Scott DA, Ronai ZA, Osterman AL, Smith JW. Reverse TCA cycle flux through isocitrate dehydrogenases 1 and 2 is required for lipogenesis in hypoxic melanoma cells. Pigment Cell Melanoma Res 2012; 25:375-83. [PMID: 22360810 DOI: 10.1111/j.1755-148x.2012.00989.x] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The tricarboxylic acid (TCA) cycle is the central hub of oxidative metabolism, running in the classic forward direction to provide carbon for biosynthesis and reducing agents for generation of ATP. Our metabolic tracer studies in melanoma cells showed that in hypoxic conditions the TCA cycle is largely disconnected from glycolysis. By studying the TCA branch point metabolites, acetyl CoA and citrate, as well as the metabolic endpoint glutamine and fatty acids, we developed a comprehensive picture of the rewiring of the TCA cycle that occurs in hypoxia. Hypoxic tumor cells maintain proliferation by running the TCA cycle in reverse. The source of carbon for acetyl CoA, citrate, and fatty acids switches from glucose in normoxia to glutamine in hypoxia. This hypoxic flux from glutamine into fatty acids is mediated by reductive carboxylation. This reductive carboxylation is catalyzed by two isocitrate dehydrogenases, IDH1 and IDH2. Their combined action is necessary and sufficient to effect the reverse TCA flux and maintain cellular viability.
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Affiliation(s)
- Fabian V Filipp
- Sanford-Burnham Medical Research Institute, Cancer Research Center, La Jolla, CA, USA.
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14
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Des Rosiers C, Labarthe F, Lloyd SG, Chatham JC. Cardiac anaplerosis in health and disease: food for thought. Cardiovasc Res 2011; 90:210-9. [PMID: 21398307 DOI: 10.1093/cvr/cvr055] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
There has been a resurgence of interest for the field of cardiac metabolism catalysed by the increased need for new therapeutic targets for patients with heart failure. The primary focus of research in this area to date has been on the impact of substrate selection for oxidative energy metabolism; however, anaplerotic metabolism also has significant interest for its potential cardioprotective role. Anaplerosis refers to metabolic pathways that replenish the citric acid cycle intermediates, which are essential to energy metabolism; however, our understanding of the role and regulation of this process in the heart, particularly under pathophysiological conditions, is very limited. Therefore, the goal of this article is to provide a foundation for future directions of research on cardiac anaplerosis and heart disease. We include an overview of anaplerotic metabolism, a critical evaluation of current methods available for its quantitation in the intact heart, and a discussion of its role and regulation both in health and disease as it is currently understood based mostly on animal studies. We also consider genetic diseases affecting anaplerotic pathways in humans and acute intervention studies with anaplerotic substrates in the clinics. Finally, as future perspectives, we will share our thoughts about potential benefits and practical considerations on modalities of interventions targeting anaplerosis in heart disease, including heart failure.
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Affiliation(s)
- Christine Des Rosiers
- Department of Nutrition, Montreal Heart Institute and Université de Montréal, Montreal, QC, Canada H3C 3J7.
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15
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Li W, Bian F, Chaudhuri P, Mao X, Brunengraber H, Yu X. Delineation of substrate selection and anaplerosis in tricarboxylic acid cycle of the heart by 13C NMR spectroscopy and mass spectrometry. NMR IN BIOMEDICINE 2011; 24:176-187. [PMID: 20960584 PMCID: PMC3086566 DOI: 10.1002/nbm.1569] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 04/13/2010] [Accepted: 04/26/2010] [Indexed: 05/30/2023]
Abstract
(13)C NMR and mass spectrometry (MS) provide complementary information regarding the (13)C labeling of intermediary metabolites. Currently, these two techniques are rarely used together because of the complexity of modeling the distribution of both positional and mass isotopomers. In this study, we developed a matrix-based model for the assessment of (13)C label distribution in the tricarboxylic acid cycle and related metabolites. The model was applied to the analysis of NMR- and MS-measured (13)C isotopomers for quantification of substrate utilization and anaplerotic fluxes in isolated perfused rat hearts. NMR and MS data were acquired from two groups of rat hearts perfused with substrates in complementary labeling patterns, i.e. the (13)C-PAL + GLC group (0.6 mM [(13) C(16) ]palmitate + 5.5 mM glucose) and the PAL + (13)C-GLC group (0.6 mM palmitate + 5.5 mM [(13)C(6) ]glucose). Relative flux parameters were obtained by fitting the model to the NMR data, MS data and their combination, respectively. Our results suggest that, although both NMR and MS can provide accurate quantification of substrate selection in oxidative metabolism, the accuracy of estimation of anaplerotic fluxes relies on the combination of these two experimental methods.
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Affiliation(s)
- Wei Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Fang Bian
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Priyanjana Chaudhuri
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Xian Mao
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University, Cleveland, OH, USA
| | - Xin Yu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Radiology, Case Western Reserve University, Cleveland, OH, USA
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
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16
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Jaswal JS, Keung W, Wang W, Ussher JR, Lopaschuk GD. Targeting fatty acid and carbohydrate oxidation--a novel therapeutic intervention in the ischemic and failing heart. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1333-50. [PMID: 21256164 DOI: 10.1016/j.bbamcr.2011.01.015] [Citation(s) in RCA: 266] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 12/16/2010] [Accepted: 01/11/2011] [Indexed: 12/19/2022]
Abstract
Cardiac ischemia and its consequences including heart failure, which itself has emerged as the leading cause of morbidity and mortality in developed countries are accompanied by complex alterations in myocardial energy substrate metabolism. In contrast to the normal heart, where fatty acid and glucose metabolism are tightly regulated, the dynamic relationship between fatty acid β-oxidation and glucose oxidation is perturbed in ischemic and ischemic-reperfused hearts, as well as in the failing heart. These metabolic alterations negatively impact both cardiac efficiency and function. Specifically there is an increased reliance on glycolysis during ischemia and fatty acid β-oxidation during reperfusion following ischemia as sources of adenosine triphosphate (ATP) production. Depending on the severity of heart failure, the contribution of overall myocardial oxidative metabolism (fatty acid β-oxidation and glucose oxidation) to adenosine triphosphate production can be depressed, while that of glycolysis can be increased. Nonetheless, the balance between fatty acid β-oxidation and glucose oxidation is amenable to pharmacological intervention at multiple levels of each metabolic pathway. This review will focus on the pathways of cardiac fatty acid and glucose metabolism, and the metabolic phenotypes of ischemic and ischemic/reperfused hearts, as well as the metabolic phenotype of the failing heart. Furthermore, as energy substrate metabolism has emerged as a novel therapeutic intervention in these cardiac pathologies, this review will describe the mechanistic bases and rationale for the use of pharmacological agents that modify energy substrate metabolism to improve cardiac function in the ischemic and failing heart. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Jagdip S Jaswal
- Mazankowski Alberta Heart Institute, Departments of Pediatrics and Pharmacology, University of Alberta, Edmonton, Alberta, Canada
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17
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Birkler RID, Støttrup NB, Hermannson S, Nielsen TT, Gregersen N, Bøtker HE, Andreasen MF, Johannsen M. A UPLC-MS/MS application for profiling of intermediary energy metabolites in microdialysis samples--a method for high-throughput. J Pharm Biomed Anal 2010; 53:983-90. [PMID: 20634014 DOI: 10.1016/j.jpba.2010.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 06/09/2010] [Accepted: 06/11/2010] [Indexed: 10/19/2022]
Abstract
Research within the field of metabolite profiling has already illuminated our understanding of a variety of physiological and pathological processes. Microdialysis has added further refinement to previous models and has allowed the testing of new hypotheses. In the present study, a new ultra-performance liquid chromatography/electrospray-tandem mass spectrometry (UPLC-ESI-MS/MS) method for the simultaneous detection and quantification of intermediary energy metabolites in microdialysates was developed. The targeted metabolites were mainly from the citric acid cycle in combination with pyruvic acid, lactic acid, and the ATP (adenosine triphosphate) hydrolysis product adenosine along with metabolites of adenosine. This method was successfully applied to analyze the microdialysates obtained from an experimental animal study giving insight into the hitherto unknown concentration of many interstitial energy metabolites, such as succinic acid and malic acid. With a total cycle time of 3 min, injection to injection, this method permits analysis of a much larger number of samples in comparison with conventional high performance liquid chromatography/tandem mass spectrometry HPLC-MS/MS strategies. With this novel combination where microdialysis and high sensitivity UPLC-MS/MS technique is combined within cardiologic research, new insights into the intermediary energy metabolism during ischemia-reperfusion is now feasible.
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Affiliation(s)
- Rune Isak Dupont Birkler
- Section for Toxicology and Drug Analysis, Department of Forensic Medicine, Aarhus University, Denmark
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18
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Wentz AE, d'Avignon DA, Weber ML, Cotter DG, Doherty JM, Kerns R, Nagarajan R, Reddy N, Sambandam N, Crawford PA. Adaptation of myocardial substrate metabolism to a ketogenic nutrient environment. J Biol Chem 2010; 285:24447-56. [PMID: 20529848 DOI: 10.1074/jbc.m110.100651] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Heart muscle is metabolically versatile, converting energy stored in fatty acids, glucose, lactate, amino acids, and ketone bodies. Here, we use mouse models in ketotic nutritional states (24 h of fasting and a very low carbohydrate ketogenic diet) to demonstrate that heart muscle engages a metabolic response that limits ketone body utilization. Pathway reconstruction from microarray data sets, gene expression analysis, protein immunoblotting, and immunohistochemical analysis of myocardial tissue from nutritionally modified mouse models reveal that ketotic states promote transcriptional suppression of the key ketolytic enzyme, succinyl-CoA:3-oxoacid CoA transferase (SCOT; encoded by Oxct1), as well as peroxisome proliferator-activated receptor alpha-dependent induction of the key ketogenic enzyme HMGCS2. Consistent with reduction of SCOT, NMR profiling demonstrates that maintenance on a ketogenic diet causes a 25% reduction of myocardial (13)C enrichment of glutamate when (13)C-labeled ketone bodies are delivered in vivo or ex vivo, indicating reduced procession of ketones through oxidative metabolism. Accordingly, unmetabolized substrate concentrations are higher within the hearts of ketogenic diet-fed mice challenged with ketones compared with those of chow-fed controls. Furthermore, reduced ketone body oxidation correlates with failure of ketone bodies to inhibit fatty acid oxidation. These results indicate that ketotic nutrient environments engage mechanisms that curtail ketolytic capacity, controlling the utilization of ketone bodies in ketotic states.
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Affiliation(s)
- Anna E Wentz
- Department of Medicine, Washington University, St Louis, Missouri 63108, USA
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19
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Moreno KX, Sabelhaus SM, Merritt ME, Sherry AD, Malloy CR. Competition of pyruvate with physiological substrates for oxidation by the heart: implications for studies with hyperpolarized [1-13C]pyruvate. Am J Physiol Heart Circ Physiol 2010; 298:H1556-64. [PMID: 20207817 DOI: 10.1152/ajpheart.00656.2009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carbon 13 nuclear magnetic resonance (NMR) isotopomer analysis was used to measure the rates of oxidation of long-chain fatty acids, ketones, and pyruvate to determine the minimum pyruvate concentration ([pyruvate]) needed to suppress oxidation of these alternative substrates. Substrate mixtures were chosen to represent either the fed or fasted state. At physiological [pyruvate], fatty acids and ketones supplied the overwhelming majority of acetyl-CoA. Under conditions mimicking the fed state, 3 mM pyruvate provided approximately 80% of acetyl-CoA, but under fasting conditions 6 mM pyruvate contributed only 33% of acetyl-CoA. Higher [pyruvate], 10-25 mM, was associated with transient reduced cardiac output, but overall hemodynamic performance was unchanged after equilibration. These observations suggested that 3-6 mM pyruvate in the coronary arteries would be an appropriate target for studies with hyperpolarized [1-(13)C]pyruvate. However, the metabolic products of 3 mM hyperpolarized [1-(13)C]pyruvate could not be detected in the isolated heart during perfusion with a physiological mixture of substrates including 3% albumin. In the presence of albumin even at high concentrations of pyruvate, 20 mM, hyperpolarized H(13)CO(3)(-) could be detected only in the absence of competing substrates. Highly purified albumin (but not albumin from plasma) substantially reduced the longitudinal relaxation time of [1-(13)C]pyruvate. In conclusion, studies of cardiac metabolism using hyperpolarized [1-(13)C]pyruvate are sensitive to the effects of competing substrates on pyruvate oxidation.
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Affiliation(s)
- Karlos X Moreno
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
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20
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Riazi R, Khairallah M, Cameron JM, Pencharz PB, Des Rosiers C, Robinson BH. Probing pyruvate metabolism in normal and mutant fibroblast cell lines using 13C-labeled mass isotopomer analysis and mass spectrometry. Mol Genet Metab 2009; 98:349-55. [PMID: 19640754 DOI: 10.1016/j.ymgme.2009.06.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 06/25/2009] [Accepted: 06/26/2009] [Indexed: 10/20/2022]
Abstract
Fibroblast cell lines are frequently used to diagnose genetic mitochondrial defects in children. The effect of enzyme deficiency on overall flux rate through metabolic pathways is, however, not generally considered. We have transposed an experimental paradigm that was developed for isolated perfused organs using (13)C-labeled substrates and (13)C-isotopomer analysis to probe pyruvate mitochondrial metabolism in cultured human fibroblast cell lines with normal or genetically mutant pyruvate decarboxylation (PDC) or carboxylation (PC) activity. Cells were incubated with 1mM [U-(13)C]pyruvate, and the (13)C-molar percent enrichment (MPE) of intracellular pyruvate, citrate, malate (as a surrogate of oxaloacetate) and aspartate was assessed by mass spectrometry. We estimated various flux ratios relevant to metabolic pathways involved in energy production, namely pyruvate formation, PDC, PC, and citrate recycling in the citric acid cycle (CAC). In all cell lines, exogenous pyruvate was predominately decarboxylated (PC/PDC ratios 0.01-0.3). PC-deficient cell lines displayed an expected negligible contribution of PC flux to oxaloacetate formation for citrate synthesis (PC/CS), which was associated with a greater contribution of PDC to acetyl-CoA formation (PDC/CS), and greater recycling of (13)C-labeled citrate into the CAC. In PDH-deficient cell lines, metabolic flux alterations were most apparent in cells with more than 50% reduction in enzyme activity. This led to an unexpected lower PC/CS flux ratio, while the PDC/CS flux ratio was unchanged. These data illustrate the usefulness of this approach in identifying unexpected metabolic consequences of genetic defects related to pyruvate metabolism.
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Affiliation(s)
- Roya Riazi
- Genetic and Genomic Biology, Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, Ont., Canada
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21
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Abstract
In 1963, Lancet published a paper by Randle et al. that proposed a "glucose-fatty acid cycle" to describe fuel flux between and fuel selection by tissues. The original biochemical mechanism explained the inhibition of glucose oxidation by fatty acids. Since then, the principle has been confirmed by many investigators. At the same time, many new mechanisms controlling the utilization of glucose and fatty acids have been discovered. Here, we review the known short- and long-term mechanisms involved in the control of glucose and fatty acid utilization at the cytoplasmic and mitochondrial level in mammalian muscle and liver under normal and pathophysiological conditions. They include allosteric control, reversible phosphorylation, and the expression of key enzymes. However, the complexity is formidable. We suggest that not all chapters of the Randle cycle have been written.
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Affiliation(s)
- Louis Hue
- Université Catholique de Louvain and de Duve Institute, Hormone and Metabolic Research Unit, Brussels, Belgium.
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22
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Ussher JR, Koves TR, Jaswal JS, Zhang L, Ilkayeva O, Dyck JR, Muoio DM, Lopaschuk GD. Insulin-stimulated cardiac glucose oxidation is increased in high-fat diet-induced obese mice lacking malonyl CoA decarboxylase. Diabetes 2009; 58:1766-75. [PMID: 19478144 PMCID: PMC2712785 DOI: 10.2337/db09-0011] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Whereas an impaired ability to oxidize fatty acids is thought to contribute to intracellular lipid accumulation, insulin resistance, and cardiac dysfunction, high rates of fatty acid oxidation could also impair glucose metabolism and function. We therefore determined the effects of diet-induced obesity (DIO) in wild-type (WT) mice and mice deficient for malonyl CoA decarboxylase (MCD(-/-); an enzyme promoting mitochondrial fatty acid oxidation) on insulin-sensitive cardiac glucose oxidation. RESEARCH DESIGN AND METHODS WT and MCD(-/-) mice were fed a low- or high-fat diet for 12 weeks, and intramyocardial lipid metabolite accumulation was assessed. A parallel feeding study was performed to assess myocardial function and energy metabolism (nanomoles per gram of dry weight per minute) in isolated working hearts (+/- insulin). RESULTS DIO markedly reduced insulin-stimulated glucose oxidation compared with low fat-fed WT mice (167 +/- 31 vs. 734 +/- 125; P < 0.05). MCD(-/-) mice subjected to DIO displayed a more robust insulin-stimulated glucose oxidation (554 +/- 82 vs. 167 +/- 31; P < 0.05) and less incomplete fatty acid oxidation, evidenced by a decrease in long-chain acylcarnitines compared with WT counterparts. MCD(-/-) mice had long-chain acyl CoAs similar to those of WT mice subjected to DIO but had increased triacylglycerol levels (10.92 +/- 3.72 vs. 3.29 +/- 0.62 mumol/g wet wt; P < 0.05). CONCLUSIONS DIO does not impair cardiac fatty acid oxidation or function, and there exists disassociation between myocardial lipid accumulation and insulin sensitivity. Our results suggest that MCD deficiency is not detrimental to the heart in obesity.
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Affiliation(s)
- John R. Ussher
- Cardiovascular Research Group, University of Alberta, Edmonton, Canada
| | - Timothy R. Koves
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, North Carolina
| | - Jagdip S. Jaswal
- Cardiovascular Research Group, University of Alberta, Edmonton, Canada
| | - Liyan Zhang
- Cardiovascular Research Group, University of Alberta, Edmonton, Canada
| | - Olga Ilkayeva
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, North Carolina
| | - Jason R.B. Dyck
- Cardiovascular Research Group, University of Alberta, Edmonton, Canada
| | - Deborah M. Muoio
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, North Carolina
| | - Gary D. Lopaschuk
- Cardiovascular Research Group, University of Alberta, Edmonton, Canada
- Corresponding author: Gary D. Lopaschuk,
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23
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Velázquez-Arellano A, Hernández-Esquivel MDLL, Sánchez RM, Ortega-Cuellar D, Rodríguez-Fuentes N, Cano S, León-Del-Río A, Carvajal K. Functional and metabolic implications of biotin deficiency for the rat heart. Mol Genet Metab 2008; 95:213-9. [PMID: 18824381 DOI: 10.1016/j.ymgme.2008.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 08/01/2008] [Accepted: 08/02/2008] [Indexed: 12/01/2022]
Abstract
The tricarboxylic acid (TCA) cycle is the main ATP provider for the heart. TCA carbons must be replenished by anaplerosis for normal cardiac function. Biotin is cofactor of the anaplerotic enzymes pyruvate and propionyl-CoA carboxylases. Here, we found that in biotin deficient rats, both carboxylases decreased 90% in adipose tissue, jejunum and spleen, but in heart they conserved about 60% residual activity. We then investigated if under biotin deficiency (BtDEF), the heart is able to maintain its function in vivo and in isolated conditions, and during ischemia and reperfusion, where metabolism drastically shifts from oxidative to mainly glycolytic. Neither glucose nor octanoate oxidation were severely affected in BtDEF hearts, as assessed by mechanical performance, oxygen uptake or high-energy metabolite content; however, myocardial hexokinase activity and lactate concentration were reduced in deficient hearts. When challenged by ischemia and reperfusion injury, BtDEF hearts did not suffer more damage than the controls, although they lowered significantly their performance, when changed to ischemic conditions, which may have clinical implications. Post-ischemic increase in ADP/ATP ratio was similar in both groups, but during reperfusion there was higher rhythm perturbation in BtDEF hearts. By being relatively insensitive to biotin deficiency, cardiac tissue seems to be able to replenish TCA cycle intermediates and to maintain ATP synthesis.
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Affiliation(s)
- Antonio Velázquez-Arellano
- Unidad de Genética de la Nutrición, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
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24
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Huggins C, Domenighetti A, Ritchie M, Khalil N, Favaloro J, Proietto J, Smyth G, Pepe S, Delbridge L. Functional and metabolic remodelling in GLUT4-deficient hearts confers hyper-responsiveness to substrate intervention. J Mol Cell Cardiol 2008; 44:270-80. [DOI: 10.1016/j.yjmcc.2007.11.020] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Revised: 10/18/2007] [Accepted: 11/29/2007] [Indexed: 01/14/2023]
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Duerr JM, Tucker K. Pyruvate transport in isolated cardiac mitochondria from two species of amphibian exhibiting dissimilar aerobic scope: Bufo marinus and Rana catesbeiana. ACTA ACUST UNITED AC 2007; 307:425-38. [PMID: 17583564 DOI: 10.1002/jez.396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cardiac mitochondria were isolated from Bufo marinus and Rana catesbeiana, two species of amphibian whose cardiovascular systems are adapted to either predominantly aerobic or glycolytic modes of locomotion. Mitochondrial oxidative capacity was compared using VO2 max and respiratory control ratios in the presence of a variety of substrates including pyruvate, lactate, oxaloacetate, beta-hydroxybutyrate, and octanoyl-carnitine. B. marinus cardiac mitochondria exhibited VO2 max values twice that of R. catesbeiana cardiac mitochondria when oxidizing carbohydrate substrates. Pyruvate transport was measured via a radiolabeled-tracer assay in isolated B. marinus and R. catesbeiana cardiac mitochondria. Time-course experiments described both alpha-cyano-4-hydroxycinnamate-sensitive (MCT-like) and phenylsuccinate-sensitive pyruvate uptake mechanisms in both species. Pyruvate uptake by the MCT-like transporter was enhanced in the presence of a pH gradient, whereas the phenylsuccinate-sensitive transporter was inhibited. Notably, anuran cardiac mitochondria exhibited activities of lactate dehydrogenase and pyruvate carboxylase. The presence of both transporters on the inner mitochondrial membrane affords the net uptake of monocarboxylates including pyruvate, beta-hydroxybutyrate, and lactate; the latter potentially indicating the presence of a lactate/pyruvate shuttle allowing oxidation of extramitochondrial NADH. Intramitochondrial lactate dehydrogenase and pyruvate carboxylase enables lactate to be oxidized to pyruvate or converted to anaplerotic oxaloacetate. Kinetics of the MCT-like transporter differed significantly between the two species, suggesting differences in aerobic scope may be in part attributable to differences in mitochondrial carbohydrate utilization.
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Affiliation(s)
- Jeffrey M Duerr
- Department of Biology and Chemistry, George Fox University, Newberg, Oregon 97132, USA.
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Kasumov T, Cendrowski AV, David F, Jobbins KA, Anderson VE, Brunengraber H. Mass isotopomer study of anaplerosis from propionate in the perfused rat heart. Arch Biochem Biophys 2007; 463:110-7. [PMID: 17418801 PMCID: PMC2047339 DOI: 10.1016/j.abb.2007.02.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 02/13/2007] [Indexed: 11/29/2022]
Abstract
Anaplerosis from propionate was investigated in rat hearts perfused with 0-2mM [(13)C(3)]propionate and physiological concentrations of glucose, lactate, and pyruvate. The data show that when the concentration of [(13)C(3)]propionate was raised from 0 to 2mM, total anaplerosis increased from 5% to 16% of the turnover of citric acid cycle intermediates. Then, [(13)C(3)]propionate abolished anaplerosis from endogenous substrates, glucose, lactate, and pyruvate. Also, while the contents of propionyl-CoA and methylmalonyl-CoA increased with [(13)C(3)]propionate concentration, the content of succinyl-CoA decreased, presumably via activation of succinyl-CoA hydrolysis by a decrease in free CoA. Under our conditions, [(13)C(3)]propionate was a purely anaplerotic substrate since there was no labeling of mitochondrial acetyl-CoA, reflected by the labeling of the acetyl moiety of citrate.
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Affiliation(s)
- Takhar Kasumov
- Department of Nutrition, Case Western Reserve University, Cleveland OH 44106
| | | | - France David
- Department of Nutrition, Case Western Reserve University, Cleveland OH 44106
| | - Kathryn A. Jobbins
- Department of Nutrition, Case Western Reserve University, Cleveland OH 44106
| | - Vernon E. Anderson
- Department of Biochemistry, Case Western Reserve University, Cleveland OH 44106
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University, Cleveland OH 44106
- * To whom correspondence should be addressed: Department of Nutrition, Case Western Reserve University, School of Medicine - WG 48, 10900 Euclid Avenue, Cleveland OH 44106-4954. Tel: (216)368-6429; E-mail:
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Alders DJC, Cornelussen RN, Prinzen FW, Specht PAC, Noble MIM, Drake-Holland AJ, de Kanter FJJ, van Beek JHGM. Regional sympathetic denervation affects the relation between canine local myocardial blood flow and oxygen consumption. Exp Physiol 2007; 92:541-8. [PMID: 17303649 DOI: 10.1113/expphysiol.2006.036228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Myocardial blood flow and oxygen consumption are heterogeneously distributed. Perfusion and myocardial oxygen consumption are closely correlated in the normal heart. It is unknown how this metabolism-perfusion relation is influenced by sympathetic denervation. We investigated this question in seven chloralose-anaesthetized dogs, 3-4 weeks after regional sympathetic denervation of the left circumflex coronary artery area of supply of the left ventricle. Measurements were made of local myocardial blood flow (MBF, in ml min(-1) (g dry wt)(-1)), measured with microspheres, and myocardial oxygen consumption ( , in mumol min(-1) (g dry wt)(-1)) in the same location, calculated from the (13)C spectrum of tissue extracts after intracoronary infusion of 3-(13)C-lactate. Since both innervated and denervated regions are subject to the same arterial pressure, lower blood flow indicates higher resistance. Mean MBF was 5.56 ml min(-1) (g dry wt)(-1) (heterogeneity of 3.47 ml min(-1) (g dry wt)(-1)) innervated, 7.48 ml min(-1) (g dry wt)(-1) (heterogeneity of 3.62 ml min(-1) (g dry wt)(-1)) denervated (n.s.). Significant linear relations were found between MBF and M Vo2 of individual samples within the innervated and denervated regions. The slopes of these relations were not significantly different, but the adjusted mean was significantly higher in the denervated regions (+1.92 ml min(-1) (g dry wt)(-1), an increase of 38% of the mean MBF at the pooled mean M Vo2, P = 0.028, ANCOVA). The ratio MBF/M Vo2(in ml micromol(-1)) was significantly higher, being 0.296 +/- 0.167 ml micromol(-1) in the denervated region compared with the innervated region, 0.216 +/- 0.126 ml micromol(-1), P = 0.0182, Mann-Whitney U test. These results indicate that sympathetic tone under chloralose anaesthesia imposes a moderate vasoconstrictive effect in the myocardium that is not detected by comparison of the mean blood flow or resistance.
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Affiliation(s)
- David J C Alders
- Laboratory for Physiology, Institute for Cardiovascular Research (ICaR-VU), VU University Medical Center, Amsterdam, The Netherlands
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Abstract
Fluxome analysis aims at the quantitative analysis of in vivo carbon fluxes in metabolic networks, i. e. intracellular activities of enzymes and pathways. It allows investigating the effects of genetic or environmental modifications and thus precisely provides a global perspective on the integrated genetic and metabolic regulation within the intact metabolic network. The experimental and computational approaches developed in this area have revealed fascinating insights into metabolic properties of various biological systems. Most of the comprehensive approaches for metabolic flux studies today involve isotopic tracer studies and GC-MS for measurement of the labeling pattern of metabolites. Initially developed and applied mainly in the field of biomedicine these GC-MS based metabolic flux approaches have been substantially extended and optimized during recent years and today display a key technology in metabolic physiology and biotechnology.
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Affiliation(s)
- Christoph Wittmann
- Biochemical Engineering Institute, Saarland University, Saarbrücken, Germany.
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29
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Vo TD, Palsson BO. Isotopomer analysis of myocardial substrate metabolism: a systems biology approach. Biotechnol Bioeng 2006; 95:972-83. [PMID: 16878330 DOI: 10.1002/bit.21063] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The increasing accessibility of mass isotopomer data via GC-MS and NMR technology has necessitated the use of a systematic and reliable method to take advantage of such data for flux analysis. Here we applied a nonlinear, optimization-based method to study substrate metabolism in cardiomyocytes using (13)C data from perfused mouse hearts. The myocardial metabolic network used in this study accounts for 257 reactions and 240 metabolites, which are further compartmentalized into extracellular space, cytosol, and mitochondrial matrix. Analysis of the perfused mouse heart showed that the steady-state ATP production rate was 16.6 +/- 2.3 micromol/min . gww, with 30% of the ATP coming from glycolysis. Of the four substrates available in the perfusate (glucose, pyruvate, lactate, and oleate), exogenous glucose forms the majority of cytosolic pyruvate. Pyruvate decaboxylation is significantly higher than carboxylation, suggesting that anaplerosis is low in the perfused heart. Exchange fluxes were predicted to be high for reversible enzymes in the citric acid cycle (CAC), but low in the glycolytic pathway. Pseudoketogenesis amounted to approximately 50% of the net ketone body uptake. Sensitivity analysis showed that the estimated flux distributions were relatively insensitive to experimental errors. The application of isotopomer data drastically improved the estimation of reaction fluxes compared to results computed with respect to reaction stoichiometry alone. Further study of 12 commonly used (13)C glucose mixtures showed that the mixtures of 20% [U-(13)C(6)] glucose, 80% [3 (13)C] glucose and 20% [U-(13)C(6)] glucose, 80% [4 (13)C] were best for resolving fluxes in the current network.
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Affiliation(s)
- Thuy D Vo
- Department of Bioengineering, University of California, San Diego, California 92093, USA
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Abstract
Over the past 20 years, stable isotopes combined with isotopomer analysis have proven to be a powerful approach to probe the dynamics of metabolism in various biological systems, including the heart. The aim of this paper is to demonstrate how isotopomer analysis of metabolic fluxes can provide novel insights into the myocardial phenotype. Specifically, building on our past experience using NMR spectroscopy and GC-MS as applied to investigations of cardiac energy metabolism, we highlight specific complex metabolic networks that would not be predicted by classical biochemistry or by static measurements of metabolite, protein and mRNA levels.
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Mallet RT, Sun J, Knott EM, Sharma AB, Olivencia-Yurvati AH. Metabolic cardioprotection by pyruvate: recent progress. Exp Biol Med (Maywood) 2005; 230:435-43. [PMID: 15985618 DOI: 10.1177/153537020523000701] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Pyruvate, a natural metabolic fuel and antioxidant in myocardium and other tissues, exerts a variety of cardioprotective actions when provided at supraphysiological concentrations. Pyruvate increases cardiac contractile performance and myocardial energy state, bolsters endogenous antioxidant systems, and protects myocardium from ischemia-reperfusion injury and oxidant stress. This article reviews and discusses basic and clinically oriented research conducted over the last several years that has yielded fundamental information on pyruvate's inotropic and cardioprotective mechanisms. Particular attention is placed on pyruvate's enhancement of sarcoplasmic reticular Ca2+ transport, its antioxidant properties, and its ability to mitigate reversible and irreversible myocardial injury. These research efforts are establishing the essential foundation for clinical application of pyruvate therapy in numerous settings including cardiopulmonary bypass surgery, cardiopulmonary resuscitation, myocardial stunning, and cardiac failure.
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Affiliation(s)
- Robert T Mallet
- Department of Integrative Physiology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, USA.
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Ala-Rämi A, Ylihautala M, Ingman P, Hassinen IE. Influence of calcium-induced workload transitions and fatty acid supply on myocardial substrate selection. Metabolism 2005; 54:410-20. [PMID: 15736122 DOI: 10.1016/j.metabol.2004.09.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Because of differences in energy yield and oxygen demand, the selection of oxidative fuels is important in the hypoxic or ischemic heart muscle. The aim of the present study was to clarify the contradictions observed in the effects of workload and fatty acid supply on myocardial fuel preference in isolated perfused rat hearts. Nuclear magnetic resonance spectroscopy combined with the administration of substrates labeled with the stable isotope carbon 13 and isotopomer analysis of glutamate labeling offers an opportunity to simultaneously measure metabolic fluxes in pathways feeding into the tricarboxylic acid (TCA) cycle. The work output was modulated by changes in extracellular calcium. In the presence of 5 mmol/L glucose, 0.5 mmol/L octanoate in the perfusate dominated the oxidative metabolism, and workload had little effect on the ratio of glucose to fatty acid utilization. This was the case even when the octanoate concentration was lowered to 50 micromol/L. The relative rate of replenishment of the TCA cycle intermediates was higher at a low workload. The redox state of flavoproteins in the intact heart was monitored fluorometrically to obtain an estimate of the mitochondrial reduced/oxidized nicotinamide-adenine dinucleotide ratio (NADH/NAD ratio) for assessment of the dominant level of regulation of cell respiration, and the myoglobin spectrum was simultaneously monitored to evaluate the oxygenation status of the myocardium. Commencement of octanoate infusion (50 micromol/L or 0.5 mmol/L) caused a large but transient reduction of mitochondrial NAD and, conversely, its cessation elicited NADH oxidation and rebound reduction. During glucose oxidation, an increase in workload led to oxidation of the mitochondrial NADH, but this effect was much smaller in the presence of 50 micromol/L octanoate and absent in the presence of 0.5 mmol/L. This indicates that strong control of oxygen consumption during glucose oxidation is exerted in the mitochondrial respiratory chain, whereas equal control during fatty acid oxidation is exerted within the metabolic pathway upstream from the respiratory chain. It is concluded that when a medium-chain fatty acid is available, myocardial workload and energy consumption have little influence on fuel preference and glucose oxidation remains suppressed.
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Affiliation(s)
- Antti Ala-Rämi
- Department of Medical Biochemistry and Molecular Biology, University of Oulu, FIN-90014 Oulu, Finland
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Labarthe F, Khairallah M, Bouchard B, Stanley WC, Des Rosiers C. Fatty acid oxidation and its impact on response of spontaneously hypertensive rat hearts to an adrenergic stress: benefits of a medium-chain fatty acid. Am J Physiol Heart Circ Physiol 2005; 288:H1425-36. [PMID: 15550523 DOI: 10.1152/ajpheart.00722.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The spontaneously hypertensive rat (SHR) is a model of cardiomyopathy characterized by a restricted use of exogenous long-chain fatty acid (LCFA) for energy production. The aims of the present study were to document the functional and metabolic response of the SHR heart under conditions of increased energy demand and the effects of a medium-chain fatty acid (MCFA; octanoate) supplementation in this situation. Hearts were perfused ex vivo in a working mode with physiological concentrations of substrates and hormones and subjected to an adrenergic stimulation (epinephrine, 10 μM).13C-labeled substrates were used to assess substrate selection for energy production. Compared with control Wistar rat hearts, SHR hearts showed an impaired response to the adrenergic stimulation as reflected by 1) a smaller increase in contractility and developed pressure, 2) a faster decline in the aortic flow, and 3) greater cardiac tissue damage (lactate dehydrogenase release: 1,577 ± 118 vs. 825 ± 44 mU/min, P < 0.01). At the metabolic level, SHR hearts presented 1) a reduced exogenous LCFA contribution to the citric acid cycle flux (16 ± 1 vs. 44 ± 4%, P < 0.001) and an enhanced contribution of endogenous substrates (20 ± 4 vs. 1 ± 4%, P < 0.01); and 2) an increased lactate production from glycolysis, with a greater lactate-to-pyruvate production ratio. Addition of 0.2 mM octanoate reduced lactate dehydrogenase release (1,145 ± 155 vs. 1,890 ± 89 mU/min, P < 0.001) and increased exogenous fatty acid contribution to energy metabolism (23.7 ± 1.3 vs. 15.8 ± 0.8%, P < 0.01), which was accompanied by an equivalent decrease in unlabeled endogenous substrate contribution, possibly triglycerides (11.6 ± 1.5 vs. 19.0 ± 1.2%, P < 0.01). Taken altogether, these results demonstrate that the SHR heart shows an impaired capacity to withstand an acute adrenergic stress, which can be improved by increasing the contribution of exogenous fatty acid oxidation to energy production by MCFA supplementation.
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Affiliation(s)
- François Labarthe
- Department of Nutrition, University of Montreal, Montreal, Quebec, Canada
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Abstract
Oxidative metabolism of blood-borne fuels provides myocardium the energy required to sustain its contractile performance. Recent research has revealed that, in addition to supplying energy, certain fuels are able to detoxify harmful oxidants and bolster the myocardium's endogenous antioxidant defenses. These antioxidant capabilities could potentially protect the myocardium from the ravages of reactive oxygen and nitrogen intermediates generated upon reperfusion of ischemic myocardium. This article reviews experimental evidence that two fuels, pyruvate and acetoacetate, provide such antioxidant protection. Pyruvate's antioxidant properties stem in part from its alpha-keto carboxylate structure, which enables it to directly, non-enzymatically neutralize peroxides and peroxynitrite. Also, citrate, which accumulates in pyruvate-perfused myocardium following anaplerotic pyruvate carboxylation, supports NADPH production to maintain glutathione:glutathione disulfide (GSH/GSSG) redox potential, the central component of the myocardial antioxidant system. Like pyruvate, acetoacetate restores GSH/GSSG and increases contractile function of post-ischemic stunned myocardium, although some of its antioxidant mechanisms may differ from pyruvate's. Both compounds restore beta-adrenergic signaling and inotropism, which are compromised in stunned myocardium. N-acetylcysteine, a pharmacological antioxidant that does not provide energy, duplicated the salutary effects of pyruvate and acetoacetate on post-ischemic gamma-adrenergic signaling and GSH/GSSG. These findings reveal novel, energy-independent mechanisms for enhancement of post-ischemic cardiac performance by metabolic fuels.
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Affiliation(s)
- Robert T Mallet
- Department of Integrative Physiology and Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA.
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Des Rosiers C, Lloyd S, Comte B, Chatham JC. A critical perspective of the use of (13)C-isotopomer analysis by GCMS and NMR as applied to cardiac metabolism. Metab Eng 2004; 6:44-58. [PMID: 14734255 DOI: 10.1016/j.ymben.2003.10.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The aim of this article is to provide a guide for metabolic physiologists and bioengineers to the combined use of gas chromatography-mass spectrometry (GCMS) and nuclear magnetic resonance (NMR) in stable isotope investigations in any biological systems. Building on our past experience with these two techniques, as applied separately to the investigation of citric acid metabolism in the ex vivo perfused rat heart we initiated a collaborative study for their critical evaluation. This article, which expands on our previous work (Mol. Cel. Biol., 2003), directly compares GCMS- and NMR-determined 13C-isotopomer and flux data obtained from ex vivo rat heart perfusion studies with 13C-substrates. Overall we have found excellent agreement between the 13C-enrichments of GCMS- and NMR-determined citric acid cycle metabolites (citrate, 2-ketoglutarate, succinate and malate) and glutamate; however the unlabeled component (M) was consistently underestimated by NMR. Despite this discrepancy there was reasonably good agreement in the relative fluxes of 13C-substrates through the citric acid cycle determined by the two techniques. Nevertheless, further investigations appear necessary before maximal advantage can be taken of the complementary 13C-isotopomer and flux data of GCMS and NMR for probing the dynamics of cellular metabolism.
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Affiliation(s)
- Christine Des Rosiers
- The Department of Nutrition & CHUM Research Center, University of Montreal, Montreal, Que, Canada H3C 3J7.
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Wang P, Chatham JC. Onset of diabetes in Zucker diabetic fatty (ZDF) rats leads to improved recovery of function after ischemia in the isolated perfused heart. Am J Physiol Endocrinol Metab 2004; 286:E725-36. [PMID: 14722022 DOI: 10.1152/ajpendo.00295.2003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to determine whether the transition from insulin resistance to hyperglycemia in a model of type 2 diabetes leads to intrinsic changes in the myocardium that increase the sensitivity to ischemic injury. Hearts from 6-, 12-, and 24-wk-old lean (Control) and obese Zucker diabetic fatty (ZDF) rats were isolated, perfused, and subjected to 30 min of low-flow ischemia (LFI) and 60 min of reperfusion. At 6 wk, ZDF animals were insulin resistant but not hyperglycemic. By 12 wk, the ZDF group was hyperglycemic and became progressively worse by 24 wk. In spontaneously beating hearts rate-pressure product (RPP) was depressed in the ZDF groups compared with age-matched Controls, primarily due to lower heart rate. Pacing significantly increased RPP in all ZDF groups; however, this was accompanied by a significant decrease in left ventricular developed pressure. There was also greater contracture during LFI in the ZDF groups compared with the Control group; surprisingly, however, functional recovery upon reperfusion was significantly higher in the diabetic 12- and 24-wk ZDF groups compared with age-matched Control groups and the 6-wk ZDF group. This improvement in recovery in the ZDF diabetic groups was independent of substrate availability, severity of ischemia, and duration of diabetes. These data demonstrate that, although the development of type 2 diabetes leads to progressive contractile and metabolic abnormalities during normoxia and LFI, it was not associated with increased susceptibility to ischemic injury.
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Affiliation(s)
- Peipei Wang
- Division of Cardiovascular Disease, Department of Medicine, The Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Al 35294-0005, USA
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Vincent G, Bouchard B, Khairallah M, Des Rosiers C. Differential modulation of citrate synthesis and release by fatty acids in perfused working rat hearts. Am J Physiol Heart Circ Physiol 2004; 286:H257-66. [PMID: 12933348 DOI: 10.1152/ajpheart.00717.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to test the effect of increasing fatty acid concentrations on substrate fluxes through pathways leading to citrate synthesis and release in the heart. This was accomplished using semirecirculating work-performing rat hearts perfused with substrate mixtures mimicking the in situ milieu (5.5 mM glucose, 8 nM insulin, 1 mM lactate, 0.2 mM pyruvate, and 0.4 mM oleate-albumin) and 13C methods. Raising the fatty acid concentration from 0.4 to 1 mM with long-chain oleate or medium-chain octanoate resulted in a lowering ( approximately 20%) of cardiac output and efficiency with unaltered O2 consumption. At the metabolic level, beyond the expected effects of high fatty acid levels on the contribution of pyruvate decarboxylation (reduced >3-fold) and beta-oxidation (enhanced approximately 3-fold) to citrate synthesis, there was also a 2.4-fold lowering of anaplerotic pyruvate carboxylation. Despite the dual inhibitory effect of high fatty acids on pyruvate decarboxylation and carboxylation, tissue citrate levels were twofold higher, but citrate release rates remained unchanged at 11-14 nmol/min, representing <0.5% of citric acid cycle flux. A similar trend was observed for most metabolic parameters after oleate or octanoate addition. Together, these results emphasize a differential modulation of anaplerotic pyruvate carboxylation and citrate release in the heart by fatty acids. We interpret the lack of effects of high fatty acid concentrations on citrate release rates as suggesting that, under physiological conditions, this process is maximal, probably limited by the activity of its mitochondrial or plasma membrane transporter. Limited citrate release at high fatty acid concentrations may have important consequences for the heart's fuel metabolism and function.
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Affiliation(s)
- Genevieve Vincent
- Department of Biochemistry, Université de Montréal, Montréal, Quebéc, Canada H2L 4M1
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Khairallah M, Labarthe F, Bouchard B, Danialou G, Petrof BJ, Des Rosiers C. Profiling substrate fluxes in the isolated working mouse heart using 13C-labeled substrates: focusing on the origin and fate of pyruvate and citrate carbons. Am J Physiol Heart Circ Physiol 2003; 286:H1461-70. [PMID: 14670819 DOI: 10.1152/ajpheart.00942.2003] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The availability of genetically modified mice requires the development of methods to assess heart function and metabolism in the intact beating organ. With the use of radioactive substrates and ex vivo perfusion of the mouse heart in the working mode, previous studies have documented glucose and fatty acid oxidation pathways. This study was aimed at characterizing the metabolism of other potentially important exogenous carbohydrate sources, namely, lactate and pyruvate. This was achieved by using (13)C-labeling methods. The mouse heart perfusion setup and buffer composition were optimized to reproduce conditions close to the in vivo milieu in terms of workload, cardiac functions, and substrate-hormone supply to the heart (11 mM glucose, 0.8 nM insulin, 50 microM carnitine, 1.5 mM lactate, 0.2 mM pyruvate, 5 nM epinephrine, 0.7 mM oleate, and 3% albumin). The use of three differentially (13)C-labeled carbohydrates and a (13)C-labeled long-chain fatty acid allowed the quantitative assessment of the metabolic origin and fate of tissue pyruvate as well as the relative contribution of substrates feeding acetyl-CoA (pyruvate and fatty acids) and oxaloacetate (pyruvate) for mitochondrial citrate synthesis. Beyond concurring with the notion that the mouse heart preferentially uses fatty acids for energy production (63.5 +/- 3.9%) and regulates its fuel selection according to the Randle cycle, our study reports for the first time in the mouse heart the following findings. First, exogenous lactate is the major carbohydrate contributing to pyruvate formation (42.0 +/- 2.3%). Second, lactate and pyruvate are constantly being taken up and released by the heart, supporting the concept of compartmentation of lactate and glucose metabolism. Finally, mitochondrial anaplerotic pyruvate carboxylation and citrate efflux represent 4.9 +/- 1.8 and 0.8 +/- 0.1%, respectively, of the citric acid cycle flux and are modulated by substrate supply. The described (13)C-labeling strategy combined with an experimental setup that enables continuous monitoring of physiological parameters offers a unique model to clarify the link between metabolic alterations, cardiac dysfunction, and disease development.
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Affiliation(s)
- Maya Khairallah
- Department of Experimental Medicine, McGill University, Montreal, Quebec, Canada H2L 4M1
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Olivencia-Yurvati AH, Blair JL, Baig M, Mallet RT. Pyruvate-enhanced cardioprotection during surgery with cardiopulmonary bypass. J Cardiothorac Vasc Anesth 2003; 17:715-20. [PMID: 14689411 DOI: 10.1053/j.jvca.2003.09.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES To determine whether pyruvate-fortified cardioplegia solution provides cardioprotection superior to lactate-based cardioplegia solutions in patients undergoing elective coronary revascularization, with specific attention to post-surgical recovery of left ventricular performance as well as biochemical markers of ischemic injury. DESIGN Prospective, randomized, semi-blinded human trial. SETTING Community-based academic medical center. PARTICIPANTS Thirty adult patients undergoing elective coronary artery bypass graft surgery. INTERVENTIONS Patients were randomized to two 4:1 blood cardioplegia solutions, one pyruvate enhanced and the other lactate based. Hemodynamic and laboratory variables were measured in all patients at pre-cross-clamp, post-cross-clamp, and 4, 6, 8, and 12 hours after bypass. MEASUREMENTS AND MAIN RESULTS Relative to lactate-based cardioplegia, pyruvate-fortified cardioplegia sharply increased left ventricular stroke work at 4 to 12 hours after bypass (p < 0.001), lowered coronary sinus troponin I and creatine phosphokinase-MB activities 67% (p < 0.001) and 53% (p < 0.01), respectively, and increased coronary sinus hemoglobin O(2) saturation 18% (p < 0.001). Ten patients treated with lactate cardioplegia required beta-adrenergic inotropic support postbypass, but only 4 pyruvate-treated patients required beta-adrenergic support (p = 0.067). Pyruvate cardioplegia shortened postsurgery hospitalization from 6.3 +/- 0.3 to 5.2 +/- 0.1 days (p < 0.002). CONCLUSIONS Pyruvate-fortified cardioplegia mitigated myocardial injury during coronary artery bypass surgery and facilitated postsurgical recovery of cardiac performance. Thus, pyruvate-enhanced cardioplegia may provide cardioprotection superior to lactate-based solutions during surgical cardiac arrest.
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Affiliation(s)
- Albert H Olivencia-Yurvati
- Department of Surgery, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, USA.
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Lloyd S, Brocks C, Chatham JC. Differential modulation of glucose, lactate, and pyruvate oxidation by insulin and dichloroacetate in the rat heart. Am J Physiol Heart Circ Physiol 2003; 285:H163-72. [PMID: 12793977 DOI: 10.1152/ajpheart.01117.2002] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite the fact that lactate and pyruvate are potential substrates for energy production in vivo, our understanding of the control and regulation of carbohydrate metabolism is based principally on studies where glucose is the only available carbohydrate. Therefore, the purpose of this study was to determine the contributions of lactate, pyruvate, and glucose to energy production in the isolated, perfused rat heart over a range of insulin concentrations and after activation of pyruvate dehydrogenase with dichloroacetate (DCA). Hearts were perfused with physiological concentrations of [1-13C]glucose, [U-13C]lactate, [2-13C]pyruvate, and unlabeled palmitate for 45 min. Hearts were freeze clamped, and 13C NMR glutamate isotopomer analysis was performed on tissue extracts. Glucose, lactate, and pyruvate all contributed significantly to myocardial energy production; however, in the absence of insulin, glucose contributed only 25-30% of total pyruvate oxidation. Even under conditions where carbohydrates represented >95% of substrate entering the tricarboxylic acid (TCA) cycle, we found that glucose contributed at most 50-60% of total carbohydrate oxidation. Despite being present at only 0.1 mM, pyruvate contributed between approximately 10% and 30% of total acetyl-CoA entry into the TCA cycle. We also found that insulin and DCA not only increased glucose oxidation but also exogenous pyruvate oxidation; however, lactate oxidation was not increased. The differential effects of insulin and DCA on pyruvate and lactate oxidation provide further evidence for compartmentation of cardiac carbohydrate metabolism. These results may have important implications for understanding the mechanisms underlying the beneficial effects of increasing cardiac carbohydrate metabolism.
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Affiliation(s)
- Steven Lloyd
- Department of Medicine, University of Alabama, Birmingham, AL 35294-4470, USA
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Carbone MA, Robinson BH. Expression and characterization of a human pyruvate carboxylase variant by retroviral gene transfer. Biochem J 2003; 370:275-82. [PMID: 12437512 PMCID: PMC1223164 DOI: 10.1042/bj20021397] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2002] [Revised: 10/24/2002] [Accepted: 10/30/2002] [Indexed: 11/17/2022]
Abstract
Type A pyruvate carboxylase (PC) deficiency presents mainly in the Amerindian population, specifically the Ojibwa, Cree and Micmac tribes of the Algonquin-speaking peoples. The gene for PC contains a homozygous founder mutation (G1828-->A) that results in an Ala610-->Thr amino acid substitution in Ojibwa with Type A PC deficiency. The mutation is located in the highly conserved pyruvate-binding domain of PC. The present paper describes a retroviral expression system for human PC used to analyse the effects of this mutation. We show, through immunoblot analysis, PC enzyme activity assays, reverse-transcription PCR and mitochondrial-import experiments, that this mutation is disease-causing in the Ojibwa population owing to its decreased catalytic activity, decreased steady-state levels of expression and inefficient import into the mitochondria. Our data suggest that this mutation may affect the stability of the protein, resulting in decreased steady-state levels of expression, and that it may also affect the secondary structure of the protein during the import process, thereby inhibiting proper translocation into the mitochondria, where PC is active.
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Affiliation(s)
- Mary Anna Carbone
- Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, Canada M5G 1X8
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Martini WZ, Stanley WC, Huang H, Rosiers CD, Hoppel CL, Brunengraber H. Quantitative assessment of anaplerosis from propionate in pig heart in vivo. Am J Physiol Endocrinol Metab 2003; 284:E351-6. [PMID: 12388135 DOI: 10.1152/ajpendo.00354.2002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Normal cardiac metabolism requires continuous replenishment (anaplerosis) of catalytic intermediates of the citric acid cycle. Little is known about the quantitative aspects of propionate as a substrate of in vivo anaplerosis; therefore, we measured the rate of propionate entry into the citric acid cycle in hearts of anesthetized pigs. [U-(13)C(3)]propionate (0.25 mM) was infused in a coronary artery branch for 1 h via an extracorporeal perfusion circuit, and cardiac biopsies were analyzed for the mass isotopomer distribution of citric acid cycle intermediates. Infusion of propionate did not affect myocardial oxygen consumption, heart rate, or contractile function. In the infused territory, propionate infusion did not affect uptake of glucose and lactate but decreased free fatty acid uptake by one-half (P < 0.05). Propionate extraction and uptake were 57.4 +/- 3.3% and 0.078 +/- 0.009 micromol x min(-1) x g(-1). Anaplerosis from propionate, calculated from the mass isotopomer distribution of succinate, accounted for 8.9 +/- 1.3% of the citric acid cycle flux. Propioylcarnitine release accounted for only 0.033 +/- 0.002% of propionate uptake. Methylcitrate did not accumulate. Thus administration of a low concentration of propionate appears to be a convenient and safe way to boost anaplerosis in the heart.
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Affiliation(s)
- Wenjun Z Martini
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-7139, USA
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Comte B, Vincent G, Bouchard B, Benderdour M, Des Rosiers C. Reverse flux through cardiac NADP(+)-isocitrate dehydrogenase under normoxia and ischemia. Am J Physiol Heart Circ Physiol 2002; 283:H1505-14. [PMID: 12234803 DOI: 10.1152/ajpheart.00287.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Little is known about the role of mitochondrial NADP(+)-isocitrate dehydrogenase (NADP(+)-ICDH) in the heart, where this enzyme shows its highest expression and activity. We tested the hypothesis that in the heart, NADP(+)-ICDH operates in the reverse direction of the citric acid cycle (CAC) and thereby may contribute to the fine regulation of CAC activity (Sazanov and Jackson, FEBS Lett 344: 109-116, 1994). We documented a reverse flux through this enzyme in rat hearts perfused with the medium-chain fatty acid octanoate using [U-(13)C(5)]glutamate and mass isotopomer analysis of tissue citrate (Comte et al., J Biol Chem 272: 26117-26124, 1997). In this study, we assessed the significance of our previous finding by perfusing hearts with long-chain fatty acids and tested the effects of changes in O(2) supply. We showed that under all of these conditions citrate was enriched in an isotopomer containing five (13)C atoms. This isotopomer can only be explained by substrate flux through reversal of the NADP(+)-ICDH reaction, which is evaluated at 3-7% of flux through citrate synthase. Small variations in reversal fluxes induced by low-flow ischemia that mimicked hibernation occurred despite major changes in contractile function and O(2) consumption of the heart as well as citrate and succinate release rates and tissue levels. Our data show a reverse flux through NADP(+)-ICDH and support its hypothesized role in the fine regulation of CAC activity in the normoxic and O(2)-deprived heart.
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Affiliation(s)
- Blandine Comte
- Department of Nutrition, University of Montreal, Quebec H3C 3J7, Canada
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Poirier M, Vincent G, Reszko AE, Bouchard B, Kelleher JK, Brunengraber H, Des Rosiers C. Probing the link between citrate and malonyl-CoA in perfused rat hearts. Am J Physiol Heart Circ Physiol 2002; 283:H1379-86. [PMID: 12234788 DOI: 10.1152/ajpheart.00244.2002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Little is known about the sources of cytosolic acetyl-CoA used for the synthesis of malonyl-CoA, a key regulator of fatty acid oxidation in the heart. We tested the hypothesis that citrate provides acetyl-CoA for malonyl-CoA synthesis after its mitochondrial efflux and cleavage by cytosolic ATP-citrate lyase. We expanded on a previous study where we characterized citrate release from perfused rat hearts (Vincent G, Comte B, Poirier M, and Des Rosiers C. Citrate release by perfused rat hearts: a window on mitochondrial cataplerosis. Am J Physiol Endocrinol Metab 278: E846-E856, 2000). In the present study, we show that citrate release rates, ranging from 6 to 22 nmol/min, can support a net increase in malonyl-CoA concentrations induced by changes in substrate supply, at most 0.7 nmol/min. In experiments with [U-(13)C](lactate + pyruvate) and [1-(13)C]oleate, we show that the acetyl moiety of malonyl-CoA is derived from both pyruvate and long-chain fatty acids. This (13)C-labeling of malonyl-CoA occurred without any changes in its concentration. Hydroxycitrate, an inhibitor of ATP-citrate lyase, prevents increases in malonyl-CoA concentrations and decreases its labeling from [U-(13)C](lactate + pyruvate). Our data support at least a partial role of citrate in the transfer from the mitochondria to cytosol of acetyl units for malonyl-CoA synthesis. In addition, they provide a dynamic picture of malonyl-CoA metabolism: even when the malonyl-CoA concentration remains constant, there appears to be a constant need to supply acetyl-CoA from various carbon sources, both carbohydrates and lipids, for malonyl-CoA synthesis.
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Affiliation(s)
- Myriame Poirier
- Department of Biochemistry, University of Montreal, Québec, Canada H3C 3J7
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Mallet RT, Squires JE, Bhatia S, Sun J. Pyruvate restores contractile function and antioxidant defenses of hydrogen peroxide-challenged myocardium. J Mol Cell Cardiol 2002; 34:1173-84. [PMID: 12392891 DOI: 10.1006/jmcc.2002.2050] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PURPOSE Pyruvate, a natural energy-yielding fuel in myocardium, neutralizes peroxides by a direct decarboxylation reaction, and indirectly augments the glutathione (GSH) antioxidant system by generating NADPH reducing power via citrate formation. The possibility that pyruvate's antioxidant actions could mediate its enhancement of contractile performance in prooxidant-challenged myocardium was investigated in isolated working guinea-pig hearts reversibly injured by hydrogen peroxide. METHODS Hearts were challenged by 10 min perfusion with 100 microM H(2)O(2), followed by 90 min H(2)O(2)-free perfusion. Metabolic and antioxidant treatments (each 5m M) were administered at 30-90 min post-H(2)O(2). Phosphocreatine phosphorylation state, GSH/glutathione disulfide redox potential (GSH/GSSG) and key enzyme activities were measured in snap-frozen myocardium. RESULTS H(2)O(2) exposure depleted myocardial energy and antioxidant reserves and produced marked contractile impairment that persisted throughout the H(2)O(2) washout period. Relative to untreated post-H(2)O(2) myocardium, pyruvate restored contractile performance, increased GSH/GSSG 52% and maintained phosphocreatine phosphorylation state; in contrast, lactate lowered cardiac performance and phosphorylation state. Neither the pharmacological antioxidant N -acetylcysteine (NAC) nor the pyruvate analog alpha-ketobutyrate increased cardiac function; both treatments increased GSH/GSSG but lowered phosphocreatine potential. H(2)O(2) partially inactivated aconitase, creatine kinase and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), but all three enzymes spontaneously recovered during H(2)O(2) washout. Pyruvate did not further activate these enzymes and unexpectedly inhibited GAPDH by 60-70%. CONCLUSION Pyruvate promoted robust contractile recovery of H(2)O(2)-challenged myocardium by the combination of citrate-mediated antioxidant mechanisms and maintenance of myocardial energy reserves.
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Affiliation(s)
- Robert T Mallet
- Department of Integrative Physiology and Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA.
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Hall JL, Gibbons GH, Chatham JC. IGF-I promotes a shift in metabolic flux in vascular smooth muscle cells. Am J Physiol Endocrinol Metab 2002; 283:E465-71. [PMID: 12169439 DOI: 10.1152/ajpendo.00072.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
13C-nuclear magnetic resonance (NMR) spectroscopy was used to test our hypothesis that insulin-like growth factor I (IGF-I) stimulates glucose flux into both nonoxidative and oxidative pathways in vascular smooth muscle cells (VSMC). Rat VSMC were exposed to uniformly labeled [13C]glucose ([U-13C]glucose; 5.5 mM) and [3-13C]pyruvate (1 mM) in the presence and absence of IGF-I (100 ng/ml). IGF-I increased glucose flux through glycolysis and the tricarboxylic acid (TCA) cycle as well as total anaplerotic flux into the TCA cycle. Previous work in our laboratory identified an increase in GLUT1 content and glucose metabolism in neointimal VSMC that was sufficient to promote proliferation and inhibit apoptosis. To test whether IGF-I could potentiate the GLUT1-induced increased flux in the neointima, we utilized VSMC harboring constitutive overexpression of GLUT1. Indeed, IGF-I markedly potentiated the GLUT1-induced increase in glucose flux through glycolysis and the TCA cycle. Taken together, these findings demonstrate that upregulation of glucose transport through either IGF-I or increased GLUT1 content stimulates glucose flux through both nonoxidative and oxidative pathways in VSMC.
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Affiliation(s)
- Jennifer L Hall
- Cardiovascular Research Institute, Morehouse School of Medicine, Atlanta, Georgia 30310, USA.
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Roe CR, Sweetman L, Roe DS, David F, Brunengraber H. Treatment of cardiomyopathy and rhabdomyolysis in long-chain fat oxidation disorders using an anaplerotic odd-chain triglyceride. J Clin Invest 2002. [DOI: 10.1172/jci0215311] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Roe CR, Sweetman L, Roe DS, David F, Brunengraber H. Treatment of cardiomyopathy and rhabdomyolysis in long-chain fat oxidation disorders using an anaplerotic odd-chain triglyceride. J Clin Invest 2002; 110:259-69. [PMID: 12122118 PMCID: PMC151060 DOI: 10.1172/jci15311] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The current dietary treatment of long-chain fatty acid oxidation defects (high carbohydrate with medium-even-chain triglycerides and reduced amounts of long-chain fats) fails, in many cases, to prevent cardiomyopathy, rhabdomyolysis, and muscle weakness. We hypothesized that the apparent defect in energy production results from a depletion of the catalytic intermediates of the citric acid cycle via leakage through cell membranes (cataplerosis). We further hypothesized that replacing dietary medium-even-chain fatty acids (precursors of acetyl-CoA) by medium-odd-chain fatty acids (precursors of acetyl-CoA and anaplerotic propionyl-CoA) would restore energy production and improve cardiac and skeletal muscle function. We fed subjects with long-chain defects a controlled diet in which the fat component was switched from medium-even-chain triglycerides to triheptanoin. In three patients with very-long-chain acyl-CoA dehydrogenase deficiency, this treatment led rapidly to clinical improvement that included the permanent disappearance of chronic cardiomyopathy, rhabdomyolysis, and muscle weakness (for more than 2 years in one child), and of rhabdomyolysis and weakness in the others. There was no evidence of propionyl overload in these patients. The treatment has been well tolerated for up to 26 months and opens new avenues for the management of patients with mitochondrial fat oxidation disorders.
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Affiliation(s)
- Charles R Roe
- Institute of Metabolic Disease, Baylor University Medical Center, Dallas, Texas 75226, USA.
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Kasumov T, Martini WZ, Reszko AE, Bian F, Pierce BA, David F, Roe CR, Brunengraber H. Assay of the concentration and (13)C isotopic enrichment of propionyl-CoA, methylmalonyl-CoA, and succinyl-CoA by gas chromatography-mass spectrometry. Anal Biochem 2002; 305:90-6. [PMID: 12018949 DOI: 10.1006/abio.2002.5639] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We developed gas chromatography-mass spectrometry assays for the concentration and mass isotopomer distribution of propionyl-CoA, methylmalonyl-CoA, and succinyl-CoA in tissues. The assays involves perchloric acid extraction of the tissue, spiking the extract with [(2)H(5)]propionyl-CoA and [(2)H(4)]succinyl-CoA internal standards, and isolation of short-chain acyl-CoA fraction on an oligonucleotide purification cartridge. Propionyl-CoA is reacted with sarcosine and the formed N-propionylsarcosine is assayed as its pentafluorobenzyl derivative. Methylmalonyl-CoA and succinyl-CoA are hydrolyzed and the corresponding acids assayed as tert-butyl dimethylsilyl derivatives. The assay was applied to a study of [U-(13)C(3)]propionate metabolism in perfused rat livers. While propionyl-CoA is only M3 labeled, succinyl-CoA is M3, M2, and M1 labeled because of isotopic exchanges in the citric acid cycle. Methylmalonyl-CoA is M3 and M2 labeled, reflecting reversal of S-methylmalonyl-CoA mutase. Thus, our assays allow measuring the turnover of the coenzyme A derivatives involved in anaplerosis of the citric acid cycle via precursors of propionyl-CoA, i.e., propionate, odd-chain fatty acids, isoleucine, threonine, and valine.
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Affiliation(s)
- Takhar Kasumov
- Department and Nutrition, Case Western Reserve University, 11000 Cedar Road, Cleveland, OH 44106-7139, USA
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