1
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Ponomarova O, Zhang H, Li X, Nanda S, Leland TB, Fox BW, Starbard AN, Giese GE, Schroeder FC, Yilmaz LS, Walhout AJM. A D-2-hydroxyglutarate dehydrogenase mutant reveals a critical role for ketone body metabolism in Caenorhabditis elegans development. PLoS Biol 2023; 21:e3002057. [PMID: 37043428 PMCID: PMC10096224 DOI: 10.1371/journal.pbio.3002057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 02/28/2023] [Indexed: 04/13/2023] Open
Abstract
In humans, mutations in D-2-hydroxyglutarate (D-2HG) dehydrogenase (D2HGDH) result in D-2HG accumulation, delayed development, seizures, and ataxia. While the mechanisms of 2HG-associated diseases have been studied extensively, the endogenous metabolism of D-2HG remains unclear in any organism. Here, we find that, in Caenorhabditis elegans, D-2HG is produced in the propionate shunt, which is transcriptionally activated when flux through the canonical, vitamin B12-dependent propionate breakdown pathway is perturbed. Loss of the D2HGDH ortholog, dhgd-1, results in embryonic lethality, mitochondrial defects, and the up-regulation of ketone body metabolism genes. Viability can be rescued by RNAi of hphd-1, which encodes the enzyme that produces D-2HG or by supplementing either vitamin B12 or the ketone bodies 3-hydroxybutyrate (3HB) and acetoacetate (AA). Altogether, our findings support a model in which C. elegans relies on ketone bodies for energy when vitamin B12 levels are low and in which a loss of dhgd-1 causes lethality by limiting ketone body production.
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Affiliation(s)
- Olga Ponomarova
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Hefei Zhang
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Xuhang Li
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Shivani Nanda
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Thomas B. Leland
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Bennett W. Fox
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - Alyxandra N. Starbard
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Gabrielle E. Giese
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Frank C. Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States of America
| | - L. Safak Yilmaz
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Albertha J. M. Walhout
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
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2
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Head PE, Venditti CP. Anaplerosis in action. Nat Metab 2023; 5:5-7. [PMID: 36717753 PMCID: PMC10181862 DOI: 10.1038/s42255-022-00724-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Investigation of multi-omic changes and their effects on regulation of metabolic pathways confirm anaplerotic deficiencies in methylmalonic acidaemia, strengthening the need for future therapies aimed at replenishing intermediates of the tricarboxylic acid cycle.
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Affiliation(s)
- PamelaSara E Head
- National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD, USA
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Charles P Venditti
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
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3
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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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4
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Zhou M, Li D, Xie K, Xu L, Kong B, Wang X, Tang Y, Liu Y, Huang H. The short-chain fatty acid propionate improved ventricular electrical remodeling in a rat model with myocardial infarction. Food Funct 2021; 12:12580-12593. [PMID: 34813637 DOI: 10.1039/d1fo02040d] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The short-chain fatty acid (SCFA) propionate (C3), a microorganism metabolite produced by gut microbial fermentation, has parasympathetic-activation effects. The cardiac autonomic rebalancing strategy is considered as an important therapeutic approach to myocardial infarction (MI)-produced ventricular arrhythmias (VAs). Thus, our research was designed to clarify the potential functions of the SCFA propionate in VAs and cardiac electrophysiology in MI rats. A hundred adult Sprague-Dawley rats were allocated to four groups: the sham group (200 mM sodium chloride), the sham + C3 group (200 mM propionate), the MI group (200 mM sodium chloride) and the MI + C3 group (200 mM propionate). In comparison with the sham group, propionate significantly increased the parasympathetic components heart rate variability (HRV) and acetylcholine levels, prolonged cardiac repolarization, induced STAT3 phosphorylation and up-regulated the c-fos expression in nodose ganglia and solitary nucleus. Propionate intake reduced the susceptibility to VAs. MI induced by coronary ligation caused a significant increase in the sympathetic components HRV, abnormal repolarization, global repolarization dispersion, norepinephrine and inflammatory cytokines, reduction and redistribution of Connexin 43 in the infarcted border zone, and activation of NFκB, which were attenuated in the MI + C3 group. Oral propionate supplementation, as a nutritional intervention, protected the heart against MI-induced VAs and cardiac electrophysiology instability partly by parasympathetic activation based on the gut-brain axis.
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Affiliation(s)
- Mingmin Zhou
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Diwen Li
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Ke Xie
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Liao Xu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Bin Kong
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Xi Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Yanhong Tang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Yu Liu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - He Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China. .,Cardiovascular Research Institute of Wuhan University, Wuhan, China. .,Hubei Key Laboratory of Cardiology, Wuhan, China
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5
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McDonald T, Puchowicz M, Borges K. Impairments in Oxidative Glucose Metabolism in Epilepsy and Metabolic Treatments Thereof. Front Cell Neurosci 2018; 12:274. [PMID: 30233320 PMCID: PMC6127311 DOI: 10.3389/fncel.2018.00274] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/06/2018] [Indexed: 12/19/2022] Open
Abstract
There is mounting evidence that oxidative glucose metabolism is impaired in epilepsy and recent work has further characterized the metabolic mechanisms involved. In healthy people eating a traditional diet, including carbohydrates, fats and protein, the major energy substrate in brain is glucose. Cytosolic glucose metabolism generates small amounts of energy, but oxidative glucose metabolism in the mitochondria generates most ATP, in addition to biosynthetic precursors in cells. Energy is crucial for the brain to signal "normally," while loss of energy can contribute to seizure generation by destabilizing membrane potentials and signaling in the chronic epileptic brain. Here we summarize the known biochemical mechanisms that contribute to the disturbance in oxidative glucose metabolism in epilepsy, including decreases in glucose transport, reduced activity of particular steps in the oxidative metabolism of glucose such as pyruvate dehydrogenase activity, and increased anaplerotic need. This knowledge justifies the use of alternative brain fuels as sources of energy, such as ketones, TCA cycle intermediates and precursors as well as even medium chain fatty acids and triheptanoin.
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Affiliation(s)
- Tanya McDonald
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Michelle Puchowicz
- Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Karin Borges
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
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6
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Ragavan M, Kirpich A, Fu X, Burgess SC, McIntyre LM, Merritt ME. A comprehensive analysis of myocardial substrate preference emphasizes the need for a synchronized fluxomic/metabolomic research design. Am J Physiol Heart Circ Physiol 2017; 312:H1215-H1223. [PMID: 28411229 DOI: 10.1152/ajpheart.00016.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 12/16/2022]
Abstract
The heart oxidizes fatty acids, carbohydrates, and ketone bodies inside the tricarboxylic acid (TCA) cycle to generate the reducing equivalents needed for ATP production. Competition between these substrates makes it difficult to estimate the extent of pyruvate oxidation. Previously, hyperpolarized pyruvate detected propionate-mediated activation of carbohydrate oxidation, even in the presence of acetate. In this report, the optimal concentration of propionate for the activation of glucose oxidation was measured in mouse hearts perfused in Langendorff mode. This study was performed with a more physiologically relevant perfusate than the previous work. Increasing concentrations of propionate did not cause adverse effects on myocardial metabolism, as evidenced by unchanged O2 consumption, TCA cycle flux, and developed pressures. Propionate at 1 mM was sufficient to achieve significant increases in pyruvate dehydrogenase flux (3×), and anaplerosis (6×), as measured by isotopomer analysis. These results further demonstrate the potential of propionate as an aid for the correct estimation of total carbohydrate oxidative capacity in the heart. However, liquid chromotography/mass spectroscopy-based metabolomics detected large changes (~30-fold) in malate and fumarate pool sizes. This observation leads to a key observation regarding mass balance in the TCA cycle; flux through a portion of the cycle can be drastically elevated without changing the O2 consumption.
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Affiliation(s)
- Mukundan Ragavan
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida
| | - Alexander Kirpich
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida.,University of Florida Informatics Insititute, Gainesville, Florida; and
| | - Xiaorong Fu
- AIRC Division of Metabolic Mechanisms of Diseases, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Shawn C Burgess
- AIRC Division of Metabolic Mechanisms of Diseases, The University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Pharmocology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Lauren M McIntyre
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida.,University of Florida Informatics Insititute, Gainesville, Florida; and.,University of Florida Genetics Insititute, Gainesville, Florida
| | - Matthew E Merritt
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida;
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7
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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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8
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Modification of Astrocyte Metabolism as an Approach to the Treatment of Epilepsy: Triheptanoin and Acetyl-l-Carnitine. Neurochem Res 2015; 41:86-95. [DOI: 10.1007/s11064-015-1728-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 09/22/2015] [Accepted: 09/23/2015] [Indexed: 12/30/2022]
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9
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Nguyen TD, Shingu Y, Amorim PA, Schwarzer M, Doenst T. Triheptanoin Alleviates Ventricular Hypertrophy and Improves Myocardial Glucose Oxidation in Rats With Pressure Overload. J Card Fail 2015. [PMID: 26209001 DOI: 10.1016/j.cardfail.2015.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Cardiac hypertrophy is characterized by changes in substrate utilization and activity of the Krebs cycle. We assessed the effects of triheptanoin, an odd-chain fat that might support the Krebs cycle, on cardiac metabolism and function in a model of cardiac hypertrophy. METHODS AND RESULTS Rats were subjected to aortic banding (AoB) to induce pressure overload (PO). Starting at 1 week after AoB, rats were blindly fed a control diet or a special diet containing triheptanoin at 7% (T7 group) or 30% (T30 group) of total energy value. Six weeks after AoB, echocardiography revealed attenuated hypertrophy and improved diastolic function of the left ventricle. Isolated working heart perfusion showed similar cardiac power, fatty acid oxidation, substrate preference, and insulin response among groups. However, cardiac glucose oxidation (GO) was increased in the T30 group compared with the T7 and control groups. Blood levels of the odd-chain ketone body beta-hydroxypentanoate confirmed adequate bioavailability of triheptanoin. Importantly, they were directly proportional to cardiac GO. CONCLUSIONS Treatment with triheptanoin-enriched diet reduces ventricular hypertrophy and improves diastolic function in rats with PO, which is associated with enhanced cardiac GO. The results suggest targeting supplementation of the Krebs cycle to approach ventricular and metabolic remodeling in cardiac hypertrophy.
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Affiliation(s)
- T Dung Nguyen
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Yasushige Shingu
- Department of Cardiovascular and Thoracic Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan
| | - Paulo A Amorim
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Michael Schwarzer
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Torsten Doenst
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany.
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10
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Purmal C, Kucejova B, Sherry AD, Burgess SC, Malloy CR, Merritt ME. Propionate stimulates pyruvate oxidation in the presence of acetate. Am J Physiol Heart Circ Physiol 2014; 307:H1134-41. [PMID: 25320331 DOI: 10.1152/ajpheart.00407.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Flux through pyruvate dehydrogenase (PDH) in the heart may be reduced by various forms of injury to the myocardium, or by oxidation of alternative substrates in normal heart tissue. It is important to distinguish these two mechanisms because imaging of flux through PDH based on the appearance of hyperpolarized (HP) [(13)C]bicarbonate derived from HP [1-(13)C]pyruvate has been proposed as a method for identifying viable myocardium. The efficacy of propionate for increasing PDH flux in the setting of PDH inhibition by an alternative substrate was studied using isotopomer analysis paired with exams using HP [1-(13)C]pyruvate. Hearts from C57/bl6 mice were supplied with acetate (2 mM) and glucose (8.25 mM). (13)C NMR spectra were acquired in a cryogenically cooled probe at 14.1 Tesla. After addition of hyperpolarized [1-(13)C]pyruvate, (13)C NMR signals from lactate, alanine, malate, and aspartate were easily detected, in addition to small signals from bicarbonate and CO2. The addition of propionate (2 mM) increased appearance of HP [(13)C]bicarbonate >30-fold without change in O2 consumption. Isotopomer analysis of extracts from the freeze-clamped hearts indicated that acetate was the preferred substrate for energy production, glucose contribution to energy production was minimal, and anaplerosis was stimulated in the presence of propionate. Under conditions where production of acetyl-CoA is dominated by the availability of an alternative substrate, acetate, propionate markedly stimulated PDH flux as detected by the appearance of hyperpolarized [(13)C]bicarbonate from metabolism of hyperpolarized [1-(13)C]pyruvate.
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Affiliation(s)
- Colin Purmal
- School of Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Blanka Kucejova
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Chemistry, University of Texas at Dallas, Richardson, Texas; and
| | - Shawn C Burgess
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Veterans Affairs North Texas Healthcare System, Dallas, Texas
| | - Matthew E Merritt
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Chemistry, University of Texas at Dallas, Richardson, Texas; and
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11
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Hettling H, Alders DJC, Heringa J, Binsl TW, Groeneveld ABJ, van Beek JHGM. Computational estimation of tricarboxylic acid cycle fluxes using noisy NMR data from cardiac biopsies. BMC SYSTEMS BIOLOGY 2013; 7:82. [PMID: 23965343 PMCID: PMC3765389 DOI: 10.1186/1752-0509-7-82] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 08/15/2013] [Indexed: 11/16/2022]
Abstract
Background The aerobic energy metabolism of cardiac muscle cells is of major importance for the contractile function of the heart. Because energy metabolism is very heterogeneously distributed in heart tissue, especially during coronary disease, a method to quantify metabolic fluxes in small tissue samples is desirable. Taking tissue biopsies after infusion of substrates labeled with stable carbon isotopes makes this possible in animal experiments. However, the appreciable noise level in NMR spectra of extracted tissue samples makes computational estimation of metabolic fluxes challenging and a good method to define confidence regions was not yet available. Results Here we present a computational analysis method for nuclear magnetic resonance (NMR) measurements of tricarboxylic acid (TCA) cycle metabolites. The method was validated using measurements on extracts of single tissue biopsies taken from porcine heart in vivo. Isotopic enrichment of glutamate was measured by NMR spectroscopy in tissue samples taken at a single time point after the timed infusion of 13C labeled substrates for the TCA cycle. The NMR intensities for glutamate were analyzed with a computational model describing carbon transitions in the TCA cycle and carbon exchange with amino acids. The model dynamics depended on five flux parameters, which were optimized to fit the NMR measurements. To determine confidence regions for the estimated fluxes, we used the Metropolis-Hastings algorithm for Markov chain Monte Carlo (MCMC) sampling to generate extensive ensembles of feasible flux combinations that describe the data within measurement precision limits. To validate our method, we compared myocardial oxygen consumption calculated from the TCA cycle flux with in vivo blood gas measurements for 38 hearts under several experimental conditions, e.g. during coronary artery narrowing. Conclusions Despite the appreciable NMR noise level, the oxygen consumption in the tissue samples, estimated from the NMR spectra, correlates with blood-gas oxygen uptake measurements for the whole heart. The MCMC method provides confidence regions for the estimated metabolic fluxes in single cardiac biopsies, taking the quantified measurement noise level and the nonlinear dependencies between parameters fully into account.
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Affiliation(s)
- Hannes Hettling
- Centre for Integrative Bioinformatics (IBIVU), Vrije Universiteit Amsterdam, de Boelelaan 1081A, 1081 HV Amsterdam, The Netherlands.
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12
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13
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Thomas NK, Willis S, Sweetman L, Borges K. Triheptanoin in acute mouse seizure models. Epilepsy Res 2012; 99:312-7. [DOI: 10.1016/j.eplepsyres.2011.12.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/29/2011] [Accepted: 12/18/2011] [Indexed: 11/25/2022]
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14
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Phillips D, Covian R, Aponte AM, Glancy B, Taylor JF, Chess D, Balaban RS. Regulation of oxidative phosphorylation complex activity: effects of tissue-specific metabolic stress within an allometric series and acute changes in workload. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1034-48. [PMID: 22378775 DOI: 10.1152/ajpregu.00596.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The concentration of mitochondrial oxidative phosphorylation complexes (MOPCs) is tuned to the maximum energy conversion requirements of a given tissue; however, whether the activity of MOPCs is altered in response to acute changes in energy conversion demand is unclear. We hypothesized that MOPCs activity is modulated by tissue metabolic stress to maintain the energy-metabolism homeostasis. Metabolic stress was defined as the observed energy conversion rate/maximum energy conversion rate. The maximum energy conversion rate was assumed to be proportional to the concentration of MOPCs, as determined with optical spectroscopy, gel electrophoresis, and mass spectrometry. The resting metabolic stress of the heart and liver across the range of resting metabolic rates within an allometric series (mouse, rabbit, and pig) was determined from MPOCs content and literature respiratory values. The metabolic stress of the liver was high and nearly constant across the allometric series due to the proportional increase in MOPCs content with resting metabolic rate. In contrast, the MOPCs content of the heart was essentially constant in the allometric series, resulting in an increasing metabolic stress with decreasing animal size. The MOPCs activity was determined in native gels, with an emphasis on Complex V. Extracted MOPCs enzyme activity was proportional to resting metabolic stress across tissues and species. Complex V activity was also shown to be acutely modulated by changes in metabolic stress in the heart, in vivo and in vitro. The modulation of extracted MOPCs activity suggests that persistent posttranslational modifications (PTMs) alter MOPCs activity both chronically and acutely, specifically in the heart. Protein phosphorylation of Complex V was correlated with activity inhibition under several conditions, suggesting that protein phosphorylation may contribute to activity modulation with energy metabolic stress. These data are consistent with the notion that metabolic stress modulates MOPCs activity in the heart.
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Affiliation(s)
- Darci Phillips
- Laboratory of Cardiac Energetics, NHLBI, NIH, Bethesda, MD 20892-1061, USA
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15
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Borges K, Sonnewald U. Triheptanoin--a medium chain triglyceride with odd chain fatty acids: a new anaplerotic anticonvulsant treatment? Epilepsy Res 2011; 100:239-44. [PMID: 21855298 DOI: 10.1016/j.eplepsyres.2011.05.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 05/16/2011] [Accepted: 05/25/2011] [Indexed: 01/30/2023]
Abstract
The triglyceride of heptanoate (C7 fatty acid), triheptanoin, is a tasteless oil used to treat rare metabolic disorders in USA and France. Heptanoate is metabolized by β-oxidation to provide propionyl-CoA, which after carboxylation can produce succinyl-CoA, resulting in anaplerosis - the refilling of the tricarboxylic acid cycle. Heptanoate is also metabolized by the liver to the C5 ketones, β-ketopentanoate and/or β-hydroxypentanoate, which are released into the blood and thought to enter the brain via monocarboxylate transporters. Oral triheptanoin has recently been discovered to be reproducibly anticonvulsant in acute and chronic mouse seizures models. However, current knowledge on alterations of brain metabolism after triheptanoin administration and anaplerosis via propionyl-CoA carboxylation in the brain is limited. This review outlines triheptanoin's unique anticonvulsant profile and its clinical potential for the treatment of medically refractory epilepsy. Anaplerosis as a therapeutic approach for the treatment of epilepsy is discussed. More research is needed to elucidate the anticonvulsant mechanism of triheptanoin and to reveal its clinical potential for the treatment of epilepsy and other disorders of the brain.
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Affiliation(s)
- Karin Borges
- Department of Pharmacology, School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia.
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16
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Schutz PW, Struys EA, Sinclair G, Stockler S. Protective effects of d-3-hydroxybutyrate and propionate during hypoglycemic coma: clinical and biochemical insights from infant rats. Mol Genet Metab 2011; 103:179-84. [PMID: 21439874 DOI: 10.1016/j.ymgme.2011.02.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Accepted: 02/20/2011] [Indexed: 10/18/2022]
Abstract
BACKGROUND d-3-hydroxybutyrate (3OHB) is an alternative energy substrate for the brain during hypoglycemia, especially during infancy. Supplementation of 3OHB during sustained hypoglycemia in rat pups delays onset of burst suppression coma, but is associated with white matter injury and increased mortality. The biochemical basis for this ambivalent effect is not known. It may be related to an anaplerotic or gluconeogenetic deficit of 3OHB. METHODS AND RESULTS We studied clinical alertness, EEG and brain metabolites (acyl-carnitines, amino acids, glycolytic and pentose phosphate intermediates) in 13 day-old rat pups during insulin induced hypoglycemic coma and after treatment with 3OHB alone or in combination with the anaplerotic substrate propionate. Clinically, treatment with 3OHB and propionate resulted in an alert state and EEG improvement, while treatment with 3OHB alone resulted in an improved EEG but animals remained clinically comatose. Biochemically, both treatments resulted in correction of cerebral glutamate and ammonia levels but not of gluconeogenetic substrates and pentose phosphate metabolites. CONCLUSION 3OHB treatment restores glutamate metabolism but cannot restore a glycolytic or pentose phosphate pathway deficit. Additional treatment with propionate significantly improved the clinical protective effect of 3OHB in hypoglycemic coma.
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Affiliation(s)
- Peter W Schutz
- Department of Pediatrics, University of British Columbia, British Columbia Children's Hospital, 4480 Oak Street, Vancouver, BC, Canada V6H
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17
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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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18
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Kasumov T, Sharma N, Huang H, Kombu RS, Cendrowski A, Stanley WC, Brunengraber H. Dipropionylcysteine ethyl ester compensates for loss of citric acid cycle intermediates during post ischemia reperfusion in the pig heart. Cardiovasc Drugs Ther 2010; 23:459-69. [PMID: 19967553 DOI: 10.1007/s10557-009-6208-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE During reperfusion, following myocardial ischemia, uncompensated loss of citric acid cycle (CAC) intermediates may impair CAC flux and energy transduction. Propionate has an anaplerotic effect when converted to the CAC intermediate succinyl-CoA, and may improve contractile recovery during reperfusion. Antioxidant therapy with N-acetylcysteine decreases reperfusion injury. To synergize the antioxidant effects of cysteine with the anaplerotic effects of propionate, we synthesized a novel bi-functional compound, N,S-dipropionyl cysteine ethyl ester (DPNCE) and tested its anaplerotic and anti-oxidative capacity in anesthetized pigs. METHODS Ischemia was induced by a 70% reduction in left anterior descending coronary artery flow for one hour, followed by 1 h of reperfusion. After 30 min of ischemia and throughout reperfusion animals were treated with saline or intravenous DPNCE (1.5 mg x kg(-1) x min(-1), n = 8/group). Arterial concentrations and myocardial propionate, cysteine, free fatty acids, glucose and lactate uptakes, cardiac mechanical functions, myocardial content of CAC intermediates and oxidative stress were assessed. RESULTS Ischemia resulted in reduction in myocardial tissue concentration of CAC intermediates. DPNCE treatment elevated arterial propionate and cysteine concentrations and myocardial propionate uptake, and increased myocardial concentrations of citrate, succinate, fumarate, and malate compared to saline treated animals. DPNCE treatment did not affect blood pressure or myocardial contractile function, but increased arterial free fatty acid concentration and myocardial fatty acid uptake. Arterial cysteine concentration was elevated by DPNCE, but there was negligible myocardial cysteine uptake, and no change in markers of oxidative stress. CONCLUSION DPNCE elevated arterial cysteine and propionate, and increased myocardial concentration of CAC intermediates, but did not affect mechanical function or oxidative stress.
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Affiliation(s)
- Takhar Kasumov
- Department Nutrition, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
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19
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Binsl TW, Alders DJ, Heringa J, Groeneveld AJ, van Beek JH. Computational quantification of metabolic fluxes from a single isotope snapshot: application to an animal biopsy. Bioinformatics 2010; 26:653-60. [DOI: 10.1093/bioinformatics/btq018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Puchowicz MA, Zechel JL, Valerio J, Emancipator DS, Xu K, Pundik S, LaManna JC, Lust WD. Neuroprotection in diet-induced ketotic rat brain after focal ischemia. J Cereb Blood Flow Metab 2008; 28:1907-16. [PMID: 18648382 PMCID: PMC3621146 DOI: 10.1038/jcbfm.2008.79] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Neuroprotective properties of ketosis may be related to the upregulation of hypoxia inducible factor (HIF)-1alpha, a primary constituent associated with hypoxic angiogenesis and a regulator of neuroprotective responses. The rationale that the utilization of ketones by the brain results in elevation of intracellular succinate, a known inhibitor of prolyl hydroxylase (the enzyme responsible for the degradation of HIF-1alpha) was deemed as a potential mechanism of ketosis on the upregulation of HIF-1alpha. The neuroprotective effect of diet-induced ketosis (3 weeks of feeding a ketogenic diet), as pretreatment, on infarct volume, after reversible middle cerebral artery occlusion (MCAO), and the upregulation of HIF-1alpha were investigated. The effect of beta-hydroxybutyrate (BHB), as a pretreatment, via intraventricular infusion (4 days of infusion before stroke) was also investigated following MCAO. Levels of HIF-1alpha and Bcl-2 (anti-apoptotic protein) proteins and succinate content were measured. A 55% or 70% reduction in infarct volume was observed with BHB infusion or diet-induced ketosis, respectively. The levels of HIF-1alpha and Bcl-2 proteins increased threefold with diet-induced ketosis; BHB infusions also resulted in increases in these proteins. As hypothesized, succinate content increased by 55% with diet-induced ketosis and fourfold with BHB infusion. In conclusion, the biochemical link between ketosis and the stabilization of HIF-1alpha is through the elevation of succinate, and both HIF-1alpha stabilization and Bcl-2 upregulation play a role in ketone-induced neuroprotection in the brain.
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Affiliation(s)
- Michelle A Puchowicz
- Department of Anatomy, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4930, USA.
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Nolan RP, Fenley AP, Lee K. Identification of distributed metabolic objectives in the hypermetabolic liver by flux and energy balance analysis. Metab Eng 2005; 8:30-45. [PMID: 16289779 DOI: 10.1016/j.ymben.2005.08.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 08/04/2005] [Accepted: 08/09/2005] [Indexed: 11/30/2022]
Abstract
A methodology for inferring distributed metabolic objectives from time series flux data is developed by combining metabolic flux analysis, pathway identification, free energy balances, and nested optimization. This methodology is used to investigate the metabolic response of the rat liver to burn injury-induced whole body inflammation. Gibbs free energy changes were computed for stoichiometrically balanced sequences of reactions, or pathways, rather than individual reactions, to account for energetic coupling between reactions. Systematic enumeration of pathways proceeded by elementary flux mode (EFM) analysis. Together with stoichiometric balances and external metabolite flux measurements, the DeltaG(PATH)(o) criterion provided sufficient constraints to solve a series of nested optimization problems on the metabolic goal functions and associated flux distributions of fasted livers during the first-week time course of burn injury. The optimization results suggest that there is a consistent metabolic goal function for the liver that is insensitive to the changing metabolic burdens experienced by the liver during the first-week time course. As defined by the goal function coefficients, the global metabolic objective was to distribute the metabolic resources between amino acid metabolism and ketone body synthesis. These findings point to a role for the time-invariant structure of the metabolic reaction network, expressed as stoichiometric and thermodynamic constraints, in shaping the cellular metabolic objective.
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Affiliation(s)
- Ryan P Nolan
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA 02155, USA
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22
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Okere IC, McElfresh TA, Brunengraber DZ, Martini W, Sterk JP, Huang H, Chandler MP, Brunengraber H, Stanley WC. Differential effects of heptanoate and hexanoate on myocardial citric acid cycle intermediates following ischemia-reperfusion. J Appl Physiol (1985) 2005; 100:76-82. [PMID: 16141384 DOI: 10.1152/japplphysiol.00255.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the normal heart, there is loss of citric acid cycle (CAC) intermediates that is matched by the entry of intermediates from outside the cycle, a process termed anaplerosis. Previous in vitro studies suggest that supplementation with anaplerotic substrates improves cardiac function during myocardial ischemia and/or reperfusion. The present investigation assessed whether treatment with the anaplerotic medium-chain fatty acid heptanoate improves contractile function during ischemia and reperfusion. The left anterior descending coronary artery of anesthetized pigs was subjected to 60 min of 60% flow reduction and 30 min of reperfusion. Three treatment groups were studied: saline control, heptanoate (0.4 mM), or hexanoate as a negative control (0.4 mM). Treatment was initiated after 30 min of ischemia and continued through reperfusion. Myocardial CAC intermediate content was not affected by ischemia-reperfusion; however, treatment with heptanoate resulted in a more than twofold increase in fumarate and malate, with no change in citrate and succinate, while treatment with hexanoate did not increase fumarate or malate but increased succinate by 1.8-fold. There were no differences among groups in lactate exchange, glucose oxidation, oxygen consumption, and contractile power. In conclusion, despite a significant increase in the content of carbon-4 CAC intermediates, treatment with heptanoate did not result in improved mechanical function of the heart in this model of reversible ischemia-reperfusion. This suggests that reduced anaplerosis and CAC dysfunction do not play a major role in contractile and metabolic derangements observed with a 60% decrease in coronary flow followed by reperfusion.
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Affiliation(s)
- Isidore C Okere
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, Ohio 44106-4970, USA
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Stanley WC, Recchia FA, Lopaschuk GD. Myocardial substrate metabolism in the normal and failing heart. Physiol Rev 2005; 85:1093-129. [PMID: 15987803 DOI: 10.1152/physrev.00006.2004] [Citation(s) in RCA: 1392] [Impact Index Per Article: 73.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The alterations in myocardial energy substrate metabolism that occur in heart failure, and the causes and consequences of these abnormalities, are poorly understood. There is evidence to suggest that impaired substrate metabolism contributes to contractile dysfunction and to the progressive left ventricular remodeling that are characteristic of the heart failure state. The general concept that has recently emerged is that myocardial substrate selection is relatively normal during the early stages of heart failure; however, in the advanced stages there is a downregulation in fatty acid oxidation, increased glycolysis and glucose oxidation, reduced respiratory chain activity, and an impaired reserve for mitochondrial oxidative flux. This review discusses 1) the metabolic changes that occur in chronic heart failure, with emphasis on the mechanisms that regulate the changes in the expression of metabolic genes and the function of metabolic pathways; 2) the consequences of these metabolic changes on cardiac function; 3) the role of changes in myocardial substrate metabolism on ventricular remodeling and disease progression; and 4) the therapeutic potential of acute and long-term manipulation of cardiac substrate metabolism in heart failure.
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Affiliation(s)
- William C Stanley
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, Ohio 44106-4970, USA.
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Zhou L, Salem JE, Saidel GM, Stanley WC, Cabrera ME. Mechanistic model of cardiac energy metabolism predicts localization of glycolysis to cytosolic subdomain during ischemia. Am J Physiol Heart Circ Physiol 2005; 288:H2400-11. [PMID: 15681693 DOI: 10.1152/ajpheart.01030.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A new multidomain mathematical model of cardiac cellular metabolism was developed to simulate metabolic responses to reduced myocardial blood flow. The model is based on mass balances and reaction kinetics that describe transport and metabolic processes of 31 key chemical species in cardiac tissue. The model has three distinct domains (blood, cytosol, and mitochondria) with interdomain transport of chemical species. In addition to distinguishing between cytosol and mitochondria, the model includes a subdomain in the cytosol to account for glycolytic metabolic channeling. Myocardial ischemia was induced by a 60% reduction in coronary blood flow, and model simulations were compared with experimental data from anesthetized pigs. Simulations with a previous model without compartmentation showed a slow activation of glycogen breakdown and delayed lactate production compared with experimental results. The addition of a subdomain for glycolysis resulted in simulations showing faster rates of glycogen breakdown and lactate production that closely matched in vivo experimental data. The dynamics of redox (NADH/NAD+) and phosphorylation (ADP/ATP) states were also simulated. These controllers are coupled to energy transfer reactions and play key regulatory roles in the cytosol and mitochondria. Simulations showed a similar dynamic response of the mitochondrial redox state and the rate of pyruvate oxidation during ischemia. In contrast, the cytosolic redox state displayed a time response similar to that of lactate production. In conclusion, this novel mechanistic model effectively predicted the rapid activation of glycogen breakdown and lactate production at the onset of ischemia and supports the concept of localization of glycolysis to a subdomain of the cytosol.
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Affiliation(s)
- Lufang Zhou
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106-6011, USA
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Sharma N, Okere IC, Brunengraber DZ, McElfresh TA, King KL, Sterk JP, Huang H, Chandler MP, Stanley WC. Regulation of pyruvate dehydrogenase activity and citric acid cycle intermediates during high cardiac power generation. J Physiol 2004; 562:593-603. [PMID: 15550462 PMCID: PMC1665507 DOI: 10.1113/jphysiol.2004.075713] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A high rate of cardiac work increases citric acid cycle (CAC) turnover and flux through pyruvate dehydrogenase (PDH); however, the mechanisms for these effects are poorly understood. We tested the hypotheses that an increase in cardiac energy expenditure: (1) activates PDH and reduces the product/substrate ratios ([NADH]/[NAD(+)] and [acetyl-CoA]/[CoA-SH]); and (2) increases the content of CAC intermediates. Measurements were made in anaesthetized pigs under control conditions and during 15 min of a high cardiac workload induced by dobutamine (Dob). A third group was made hyperglycaemic (14 mm) to stimulate flux through PDH during the high work state (Dob + Glu). Glucose and fatty acid oxidation were measured with (14)C-glucose and (3)H-oleate. Compared with control, the high workload groups had a similar increase in myocardial oxygen consumption ( and cardiac power. Dob increased PDH activity and glucose oxidation above control, but did not reduce the [NADH]/[NAD(+)] and [acetyl-CoA]/[CoA-SH] ratios, and there were no differences between the Dob and Dob + Glu groups. An additional group was treated with Dob + Glu and oxfenicine (Oxf) to inhibit fatty acid oxidation: this increased [CoA-SH] and glucose oxidation compared with Dob; however, there was no further activation of PDH or decrease in the [NADH]/[NAD(+)] ratio. Content of the 4-carbon CAC intermediates succinate, fumarate and malate increased 3-fold with Dob, but there was no change in citrate content, and the Dob + Glu and Dob + Glu + Oxf groups were not different from Dob. In conclusion, compared with normal conditions, at high myocardial energy expenditure (1) the increase in flux through PDH is regulated by activation of the enzyme complex and continues to be partially controlled through inhibition by fatty acid oxidation, and (2) there is expansion of the CAC pool size at the level of 4-carbon intermediates that is largely independent of myocardial fatty acid oxidation.
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Affiliation(s)
- Naveen Sharma
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4970, USA
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