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van Ewijk PA, Schrauwen-Hinderling VB, Bekkers SCAM, Glatz JFC, Wildberger JE, Kooi ME. MRS: a noninvasive window into cardiac metabolism. NMR IN BIOMEDICINE 2015; 28:747-66. [PMID: 26010681 DOI: 10.1002/nbm.3320] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 04/02/2015] [Accepted: 04/07/2015] [Indexed: 05/21/2023]
Abstract
A well-functioning heart requires a constant supply of a balanced mixture of nutrients to be used for the production of adequate amounts of adenosine triphosphate, which is the main energy source for most cellular functions. Defects in cardiac energy metabolism are linked to several myocardial disorders. MRS can be used to study in vivo changes in cardiac metabolism noninvasively. MR techniques allow repeated measurements, so that disease progression and the response to treatment or to a lifestyle intervention can be monitored. It has also been shown that MRS can predict clinical heart failure and death. This article focuses on in vivo MRS to assess cardiac metabolism in humans and experimental animals, as experimental animals are often used to investigate the mechanisms underlying the development of metabolic diseases. Various MR techniques, such as cardiac (31) P-MRS, (1) H-MRS, hyperpolarized (13) C-MRS and Dixon MRI, are described. A short overview of current and emerging applications is given. Cardiac MRS is a promising technique for the investigation of the relationship between cardiac metabolism and cardiac disease. However, further optimization of scan time and signal-to-noise ratio is required before broad clinical application. In this respect, the ongoing development of advanced shimming algorithms, radiofrequency pulses, pulse sequences, (multichannel) detection coils, the use of hyperpolarized nuclei and scanning at higher magnetic field strengths offer future perspective for clinical applications of MRS.
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Affiliation(s)
- Petronella A van Ewijk
- Maastricht University Medical Center, Human Biology, Maastricht, the Netherlands
- Maastricht University Medical Center, Radiology, Maastricht, the Netherlands
- Maastricht University Medical Center, NUTRIM - School for Nutrition, Toxicology and Metabolism, Maastricht, the Netherlands
| | - Vera B Schrauwen-Hinderling
- Maastricht University Medical Center, Human Biology, Maastricht, the Netherlands
- Maastricht University Medical Center, Radiology, Maastricht, the Netherlands
- Maastricht University Medical Center, NUTRIM - School for Nutrition, Toxicology and Metabolism, Maastricht, the Netherlands
| | | | - Jan F C Glatz
- Maastricht University Medical Center, Molecular Genetics, Maastricht, the Netherlands
- Maastricht University Medical Center, CARIM - Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
| | | | - M Eline Kooi
- Maastricht University Medical Center, Radiology, Maastricht, the Netherlands
- Maastricht University Medical Center, NUTRIM - School for Nutrition, Toxicology and Metabolism, Maastricht, the Netherlands
- Maastricht University Medical Center, CARIM - Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
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52
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Mitochondrial pyruvate transport: a historical perspective and future research directions. Biochem J 2015; 466:443-54. [PMID: 25748677 DOI: 10.1042/bj20141171] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pyruvate is the end-product of glycolysis, a major substrate for oxidative metabolism, and a branching point for glucose, lactate, fatty acid and amino acid synthesis. The mitochondrial enzymes that metabolize pyruvate are physically separated from cytosolic pyruvate pools and rely on a membrane transport system to shuttle pyruvate across the impermeable inner mitochondrial membrane (IMM). Despite long-standing acceptance that transport of pyruvate into the mitochondrial matrix by a carrier-mediated process is required for the bulk of its metabolism, it has taken almost 40 years to determine the molecular identity of an IMM pyruvate carrier. Our current understanding is that two proteins, mitochondrial pyruvate carriers MPC1 and MPC2, form a hetero-oligomeric complex in the IMM to facilitate pyruvate transport. This step is required for mitochondrial pyruvate oxidation and carboxylation-critical reactions in intermediary metabolism that are dysregulated in several common diseases. The identification of these transporter constituents opens the door to the identification of novel compounds that modulate MPC activity, with potential utility for treating diabetes, cardiovascular disease, cancer, neurodegenerative diseases, and other common causes of morbidity and mortality. The purpose of the present review is to detail the historical, current and future research investigations concerning mitochondrial pyruvate transport, and discuss the possible consequences of altered pyruvate transport in various metabolic tissues.
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53
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Vanderperre B, Bender T, Kunji ERS, Martinou JC. Mitochondrial pyruvate import and its effects on homeostasis. Curr Opin Cell Biol 2015; 33:35-41. [DOI: 10.1016/j.ceb.2014.10.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 12/15/2022]
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Seymour AML, Giles L, Ball V, Miller JJ, Clarke K, Carr CA, Tyler DJ. In vivo assessment of cardiac metabolism and function in the abdominal aortic banding model of compensated cardiac hypertrophy. Cardiovasc Res 2015; 106:249-60. [PMID: 25750189 PMCID: PMC4400188 DOI: 10.1093/cvr/cvv101] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 03/02/2015] [Indexed: 01/22/2023] Open
Abstract
Aims Left ventricular hypertrophy is an adaptive response of the heart to chronic mechanical overload and can lead to functional deterioration and heart failure. Changes in cardiac energy metabolism are considered as key to the hypertrophic remodelling process. The concurrence of obesity and hypertrophy has been associated with contractile dysfunction, and this work therefore aimed to investigate the in vivo structural, functional, and metabolic remodelling that occurs in the hypertrophied heart in the setting of a high-fat, high-sucrose, Western diet (WD). Methods and results Following induction of cardiac hypertrophy through abdominal aortic banding, male Sprague Dawley rats were exposed to either a standard diet or a WD (containing 45% fat and 16% sucrose) for up to 14 weeks. Cardiac structural and functional characteristics were determined by CINE MRI, and in vivo metabolism was investigated using hyperpolarized 13C-labelled pyruvate. Cardiac hypertrophy was observed at all time points, irrespective of dietary manipulation, with no evidence of cardiac dysfunction. Pyruvate dehydrogenase flux was unchanged in the hypertrophied animals at any time point, but increased incorporation of the 13C label into lactate was observed by 9 weeks and maintained at 14 weeks, indicative of enhanced glycolysis. Conclusion Hypertrophied hearts revealed little evidence of a switch towards increased glucose oxidation but rather an uncoupling of glycolytic metabolism from glucose oxidation. This was maintained under conditions of dietary stress provided by a WD but, at this compensated phase of hypertrophy, did not result in any contractile dysfunction.
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Affiliation(s)
- Anne-Marie L Seymour
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK
| | - Lucia Giles
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Vicky Ball
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
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Nederlof R, Eerbeek O, Hollmann MW, Southworth R, Zuurbier CJ. Targeting hexokinase II to mitochondria to modulate energy metabolism and reduce ischaemia-reperfusion injury in heart. Br J Pharmacol 2014; 171:2067-79. [PMID: 24032601 DOI: 10.1111/bph.12363] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/12/2013] [Accepted: 08/15/2013] [Indexed: 12/29/2022] Open
Abstract
Mitochondrially bound hexokinase II (mtHKII) has long been known to confer cancer cells with their resilience against cell death. More recently, mtHKII has emerged as a powerful protector against cardiac cell death. mtHKII protects against ischaemia-reperfusion (IR) injury in skeletal muscle and heart, attenuates cardiac hypertrophy and remodelling, and is one of the major end-effectors through which ischaemic preconditioning protects against myocardial IR injury. Mechanisms of mtHKII cardioprotection against reperfusion injury entail the maintenance of regulated outer mitochondrial membrane (OMM) permeability during ischaemia and reperfusion resulting in stabilization of mitochondrial membrane potential, the prevention of OMM breakage and cytochrome C release, and reduced reactive oxygen species production. Increasing mtHK may also have important metabolic consequences, such as improvement of glucose-induced insulin release, prevention of acidosis through enhanced coupling of glycolysis and glucose oxidation, and inhibition of fatty acid oxidation. Deficiencies in expression and distorted cellular signalling of HKII may contribute to the altered sensitivity of diabetes to cardiac ischaemic diseases. The interaction of HKII with the mitochondrion constitutes a powerful endogenous molecular mechanism to protect against cell death in almost all cell types examined (neurons, tumours, kidney, lung, skeletal muscle, heart). The challenge now is to harness mtHKII in the treatment of infarction, stroke, elective surgery and transplantation. Remote ischaemic preconditioning, metformin administration and miR-155/miR-144 manipulations are potential means of doing just that.
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Affiliation(s)
- Rianne Nederlof
- Laboratory of Experimental Intensive Care and Anesthesiology, Department of Anesthesiology, University of Amsterdam, Amsterdam, The Netherlands
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Nederlof R, Eerbeek O, Hollmann MW, Southworth R, Zuurbier CJ. Targeting hexokinase II to mitochondria to modulate energy metabolism and reduce ischaemia-reperfusion injury in heart. Br J Pharmacol 2014. [PMID: 24032601 DOI: 10.1111/bph.12363];] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mitochondrially bound hexokinase II (mtHKII) has long been known to confer cancer cells with their resilience against cell death. More recently, mtHKII has emerged as a powerful protector against cardiac cell death. mtHKII protects against ischaemia-reperfusion (IR) injury in skeletal muscle and heart, attenuates cardiac hypertrophy and remodelling, and is one of the major end-effectors through which ischaemic preconditioning protects against myocardial IR injury. Mechanisms of mtHKII cardioprotection against reperfusion injury entail the maintenance of regulated outer mitochondrial membrane (OMM) permeability during ischaemia and reperfusion resulting in stabilization of mitochondrial membrane potential, the prevention of OMM breakage and cytochrome C release, and reduced reactive oxygen species production. Increasing mtHK may also have important metabolic consequences, such as improvement of glucose-induced insulin release, prevention of acidosis through enhanced coupling of glycolysis and glucose oxidation, and inhibition of fatty acid oxidation. Deficiencies in expression and distorted cellular signalling of HKII may contribute to the altered sensitivity of diabetes to cardiac ischaemic diseases. The interaction of HKII with the mitochondrion constitutes a powerful endogenous molecular mechanism to protect against cell death in almost all cell types examined (neurons, tumours, kidney, lung, skeletal muscle, heart). The challenge now is to harness mtHKII in the treatment of infarction, stroke, elective surgery and transplantation. Remote ischaemic preconditioning, metformin administration and miR-155/miR-144 manipulations are potential means of doing just that.
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Affiliation(s)
- Rianne Nederlof
- Laboratory of Experimental Intensive Care and Anesthesiology, Department of Anesthesiology, University of Amsterdam, Amsterdam, The Netherlands
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Comment A, Merritt ME. Hyperpolarized magnetic resonance as a sensitive detector of metabolic function. Biochemistry 2014; 53:7333-57. [PMID: 25369537 PMCID: PMC4255644 DOI: 10.1021/bi501225t] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
![]()
Hyperpolarized magnetic resonance
allows for noninvasive measurements
of biochemical reactions in vivo. Although this technique
provides a unique tool for assaying enzymatic activities in intact
organs, the scope of its application is still elusive for the wider
scientific community. The purpose of this review is to provide key
principles and parameters to guide the researcher interested in adopting
this technology to address a biochemical, biomedical, or medical issue.
It is presented in the form of a compendium containing the underlying
essential physical concepts as well as suggestions to help assess
the potential of the technique within the framework of specific research
environments. Explicit examples are used to illustrate the power as
well as the limitations of hyperpolarized magnetic resonance.
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Affiliation(s)
- Arnaud Comment
- Institute of Physics of Biological Systems, Ecole Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland
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58
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Dodd MS, Atherton HJ, Carr CA, Stuckey DJ, West JA, Griffin JL, Radda GK, Clarke K, Heather LC, Tyler DJ. Impaired in vivo mitochondrial Krebs cycle activity after myocardial infarction assessed using hyperpolarized magnetic resonance spectroscopy. Circ Cardiovasc Imaging 2014; 7:895-904. [PMID: 25201905 PMCID: PMC4450075 DOI: 10.1161/circimaging.114.001857] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 09/05/2014] [Indexed: 01/26/2023]
Abstract
BACKGROUND Myocardial infarction (MI) is one of the leading causes of heart failure. An increasing body of evidence links alterations in cardiac metabolism and mitochondrial function with the progression of heart disease. The aim of this work was to, therefore, follow the in vivo mitochondrial metabolic alterations caused by MI, thereby allowing a greater understanding of the interplay between metabolic and functional abnormalities. METHODS AND RESULTS Using hyperpolarized carbon-13 ((13)C)-magnetic resonance spectroscopy, in vivo alterations in mitochondrial metabolism were assessed for 22 weeks after surgically induced MI with reperfusion in female Wister rats. One week after MI, there were no detectable alterations in in vivo cardiac mitochondrial metabolism over the range of ejection fractions observed (from 28% to 84%). At 6 weeks after MI, in vivo mitochondrial Krebs cycle activity was impaired, with decreased (13)C-label flux into citrate, glutamate, and acetylcarnitine, which correlated with the degree of cardiac dysfunction. These changes were independent of alterations in pyruvate dehydrogenase flux. By 22 weeks, alterations were also seen in pyruvate dehydrogenase flux, which decreased at lower ejection fractions. These results were confirmed using in vitro analysis of enzyme activities and metabolomic profiles of key intermediates. CONCLUSIONS The in vivo decrease in Krebs cycle activity in the 6-week post-MI heart may represent an early maladaptive phase in the metabolic alterations after MI in which reductions in Krebs cycle activity precede a reduction in pyruvate dehydrogenase flux. Changes in mitochondrial metabolism in heart disease are progressive and proportional to the degree of cardiac impairment.
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Affiliation(s)
- Michael S Dodd
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Helen J Atherton
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Carolyn A Carr
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Daniel J Stuckey
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - James A West
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Julian L Griffin
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - George K Radda
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Kieran Clarke
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Lisa C Heather
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
| | - Damian J Tyler
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom (M.S.D., H.J.A., C.A.C., G.K.R., K.C., L.C.H., D.J.T.); Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom (D.J.S.); and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom (J.A.W., J.L.G.)
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Pagès G, Tan YL, Kuchel PW. Hyperpolarized [1,(13)C]pyruvate in lysed human erythrocytes: effects of co-substrate supply on reaction time courses. NMR IN BIOMEDICINE 2014; 27:1203-1210. [PMID: 25111006 DOI: 10.1002/nbm.3176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/12/2014] [Accepted: 07/10/2014] [Indexed: 06/03/2023]
Abstract
Hyperpolarized [1,(13)C]pyruvate was injected rapidly into haemolysates in which hydrolysis of nicotinamide adenine dinucleotide (phosphate) (NAD(P))/NAD(P)H had been inhibited with nicotinamide. Haemolysates provide a stable glycolytic system in which membrane permeability is not a flux-controlling step, and they enable the concentration of NADH to be adjusted experimentally while keeping the rest of the sample with the same composition as that of the cytoplasm of the cell (albeit diluted twofold at the time of injection of the [1,(13)C]pyruvate). We showed that the maximum amplitude of the (13)C NMR signal from the [1,(13)C]L-lactate, produced from [1,(13)C]pyruvate, and the time at which it occurred was dependent on NADH concentration, as predicted by enzyme-kinetic analysis. The main feature of such curves was dictated by the immediacy of the supply of the co-substrate of lactate dehydrogenase (LDH, EC 1.1.1.27), and we posit that this also pertains in vivo in various tissues including neoplasms. By constructing an appropriate mathematical model and by using a Markov-chain Monte Carlo approach, we fitted experimental data to estimate LDH and NADH concentrations. Experiments carried out with only endogenous NADH present enabled the estimation of its effective concentration in human RBCs; the ability to make this estimate is a special feature of the rapid-dissolution dynamic nuclear polarization method. We found an endogenous NADH concentration in human RBCs two to four times higher than previously reported.
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Affiliation(s)
- Guilhem Pagès
- Singapore Bioimaging Consortium, A*STAR, Singapore, 138667
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60
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Khemtong C, Carpenter NR, Lumata LL, Merritt ME, Moreno KX, Kovacs Z, Malloy CR, Sherry AD. Hyperpolarized 13C NMR detects rapid drug-induced changes in cardiac metabolism. Magn Reson Med 2014; 74:312-9. [PMID: 25168480 DOI: 10.1002/mrm.25419] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 07/01/2014] [Accepted: 07/30/2014] [Indexed: 12/27/2022]
Abstract
PURPOSE The diseased myocardium lacks metabolic flexibility and responds to stimuli differently compared with healthy hearts. Here, we report the use of hyperpolarized 13C NMR spectroscopy to detect sudden changes in cardiac metabolism in isolated, perfused rat hearts in response to adrenergic stimulation. METHODS Metabolism of hyperpolarized [1-(13)C]pyruvate was investigated in perfused rat hearts. The hearts were stimulated in situ by isoproterenol shortly after the administration of hyperpolarized [1-(13)C]pyruvate. The hyperpolarized 13C NMR results were corroborated with 1H NMR spectroscopy of tissue extracts. RESULTS Addition of isoproterenol to hearts after equilibration of hyperpolarized [1-(13)C]pyruvate into the existing lactate pool resulted in a sudden, rapid increase in hyperpolarized [1-(13)C]lactate signal within seconds after exposure to drug. The hyperpolarized H(13)CO3 (-) and hyperpolarized [1-(13)C]alanine signals were not affected by the isoproterenol-induced elevated cardiac workload. Separate experiments confirmed that the new hyperpolarized [1-(13)C]lactate signal that arises after stimulation by isoproterenol reflects a sudden increase in total tissue lactate derived from glycogen. CONCLUSION These results suggest that hyperpolarized pyruvate and 13C MRS may be useful for detecting abnormal glycogen metabolism in intact tissues.
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Affiliation(s)
- Chalermchai Khemtong
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Nicholas R Carpenter
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Lloyd L Lumata
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Matthew E Merritt
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Karlos X Moreno
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Zoltan Kovacs
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Chemistry, University of Texas at Dallas, Richardson, Texas, USA
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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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Lerche MH, Jensen PR, Karlsson M, Meier S. NMR insights into the inner workings of living cells. Anal Chem 2014; 87:119-32. [PMID: 25084065 DOI: 10.1021/ac501467x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Mathilde H Lerche
- Albeda Research , Gamle Carlsberg Vej 10, 1799 Copenhagen V, Denmark
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Deng W, Leu HB, Chen Y, Chen YH, Epperson CM, Juang C, Wang PH. Protein kinase B (PKB/AKT1) formed signaling complexes with mitochondrial proteins and prevented glycolytic energy dysfunction in cultured cardiomyocytes during ischemia-reperfusion injury. Endocrinology 2014; 155:1618-28. [PMID: 24601882 PMCID: PMC3990846 DOI: 10.1210/en.2013-1817] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Our previous studies showed that insulin stimulated AKT1 translocation into mitochondria and modulated oxidative phosphorylation complex V in cardiac muscle. This raised the possibility that mitochondrial AKT1 may regulate glycolytic oxidative phosphorylation and mitochondrial function in cardiac muscle cells. The aims of this project were to study the effects of mitochondrial AKT1 signaling on cell survival in stressed cardiomyocytes, to define the effect of mitochondrial AKT1 signaling on glycolytic bioenergetics, and to identify mitochondrial targets of AKT1 signaling in cardiomyocytes. Mitochondrial AKT1 signaling played a protective role against apoptosis and necrosis during ischemia-reperfusion stress, suppressed mitochondrial calcium overload, and alleviated mitochondrial membrane depolarization. Activation of AKT1 signaling in mitochondria increased glucose uptake, enhanced respiration efficiency, reduced superoxide generation, and increased ATP production in the cardiomyocytes. Inhibition of mitochondrial AKT attenuated insulin response, indicating that insulin regulation of ATP production required mitochondrial AKT1 signaling. A proteomic approach was used to reveal 15 novel targets of AKT1 signaling in mitochondria, including pyruvate dehydrogenase complex (PDC). We have confirmed and characterized the association of AKT1 and PDC subunits and verified a stimulatory effect of mitochondrial AKT1 on the enzymatic activity of PDC. These findings suggested that AKT1 formed protein complexes with multiple mitochondrial proteins and improved mitochondrial function in stressed cardiomyocytes. The novel AKT1 signaling targets in mitochondria may become a resource for future metabolism research.
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Affiliation(s)
- Wu Deng
- University of California Irvine Diabetes Center and Department of Medicine (W.D., H.-B.L., Y.C., Y.-H.C., C.M.E., C.J., P.H.W.), University of California Irvine, California 92697; Department of Medicine (H.-B.L.), Veterans General Hospital, and School of Medicine, National Yang-Ming University, Taipei, 11217, Taiwan; and Departments of Biological Chemistry and Physiology and Biophysics (P.H.W.), University of California Irvine, California 92697
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Keshari KR, Wilson DM. Chemistry and biochemistry of 13C hyperpolarized magnetic resonance using dynamic nuclear polarization. Chem Soc Rev 2013; 43:1627-59. [PMID: 24363044 DOI: 10.1039/c3cs60124b] [Citation(s) in RCA: 262] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The study of transient chemical phenomena by conventional NMR has proved elusive, particularly for non-(1)H nuclei. For (13)C, hyperpolarization using the dynamic nuclear polarization (DNP) technique has emerged as a powerful means to improve SNR. The recent development of rapid dissolution DNP methods has facilitated previously impossible in vitro and in vivo study of small molecules. This review presents the basics of the DNP technique, identification of appropriate DNP substrates, and approaches to increase hyperpolarized signal lifetimes. Also addressed are the biochemical events to which DNP-NMR has been applied, with descriptions of several probes that have met with in vivo success.
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Affiliation(s)
- Kayvan R Keshari
- Department of Radiology, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY 10065, USA
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Kolwicz SC, Purohit S, Tian R. Cardiac metabolism and its interactions with contraction, growth, and survival of cardiomyocytes. Circ Res 2013; 113:603-16. [PMID: 23948585 DOI: 10.1161/circresaha.113.302095] [Citation(s) in RCA: 518] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The network for cardiac fuel metabolism contains intricate sets of interacting pathways that result in both ATP-producing and non-ATP-producing end points for each class of energy substrates. The most salient feature of the network is the metabolic flexibility demonstrated in response to various stimuli, including developmental changes and nutritional status. The heart is also capable of remodeling the metabolic pathways in chronic pathophysiological conditions, which results in modulations of myocardial energetics and contractile function. In a quest to understand the complexity of the cardiac metabolic network, pharmacological and genetic tools have been engaged to manipulate cardiac metabolism in a variety of research models. In concert, a host of therapeutic interventions have been tested clinically to target substrate preference, insulin sensitivity, and mitochondrial function. In addition, the contribution of cellular metabolism to growth, survival, and other signaling pathways through the production of metabolic intermediates has been increasingly noted. In this review, we provide an overview of the cardiac metabolic network and highlight alterations observed in cardiac pathologies as well as strategies used as metabolic therapies in heart failure. Lastly, the ability of metabolic derivatives to intersect growth and survival are also discussed.
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Affiliation(s)
- Stephen C Kolwicz
- Mitochondria and Metabolism Center, Department of Anesthesiology and Pain Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA
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Josan S, Park JM, Hurd R, Yen YF, Pfefferbaum A, Spielman D, Mayer D. In vivo investigation of cardiac metabolism in the rat using MRS of hyperpolarized [1-13C] and [2-13C]pyruvate. NMR IN BIOMEDICINE 2013; 26:1680-7. [PMID: 23904148 PMCID: PMC3838505 DOI: 10.1002/nbm.3003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 04/30/2013] [Accepted: 06/23/2013] [Indexed: 05/23/2023]
Abstract
Hyperpolarized (13)C MRS allows the in vivo assessment of pyruvate dehydrogenase complex (PDC) flux, which converts pyruvate to acetyl-coenzyme A (acetyl-CoA). [1-(13)C]pyruvate has been used to measure changes in cardiac PDC flux, with demonstrated increase in (13)C-bicarbonate production after dichloroacetate (DCA) administration. With [1-(13)C]pyruvate, the (13)C label is released as (13 CO2 /(13)C-bicarbonate, and, hence, does not allow us to follow the fate of acetyl-CoA. Pyruvate labeled in the C2 position has been used to track the (13)C label into the TCA (tricarboxylic acid) cycle and measure [5-(13)C]glutamate as well as study changes in [1-(13)C]acetylcarnitine with DCA and dobutamine. This work investigates changes in the metabolic fate of acetyl-CoA in response to metabolic interventions of DCA-induced increased PDC flux in the fed and fasted state, and increased cardiac workload with dobutamine in vivo in rat heart at two different pyruvate doses. DCA led to a modest increase in the (13)C labeling of [5-(13)C]glutamate, and a considerable increase in [1-(13)C]acetylcarnitine and [1,3-(13)C]acetoacetate peaks. Dobutamine resulted in an increased labeling of [2-(13)C]lactate, [2-(13)C]alanine and [5-(13)C]glutamate. The change in glutamate with dobutamine was observed using a high pyruvate dose but not with a low dose. The relative changes in the different metabolic products provide information about the relationship between PDC-mediated oxidation of pyruvate and its subsequent incorporation into the TCA cycle compared with other metabolic pathways. Using a high dose of pyruvate may provide an improved ability to observe changes in glutamate.
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Affiliation(s)
- Sonal Josan
- SRI International, Neuroscience Program, 333 Ravenswood Ave., Menlo Park, CA 94025
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
| | - Jae Mo Park
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
- Stanford University, Department of Electrical Engineering, Stanford, CA 94305
| | - Ralph Hurd
- GE Healthcare Applied Sciences Laboratory, 333 Ravenswood Ave., Menlo Park, CA 94025
| | - Yi-Fen Yen
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
| | - Adolf Pfefferbaum
- SRI International, Neuroscience Program, 333 Ravenswood Ave., Menlo Park, CA 94025
- Stanford University, Department of Psychiatry and Behavioral Sciences, 401 Quarry Rd., Stanford, CA 94305
| | - Daniel Spielman
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
- Stanford University, Department of Electrical Engineering, Stanford, CA 94305
| | - Dirk Mayer
- SRI International, Neuroscience Program, 333 Ravenswood Ave., Menlo Park, CA 94025
- Stanford University, Department of Radiology, Lucas MRI Center, 1201 Welch Rd. Stanford, CA 94305
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Circulation: Cardiovascular Imaging
Editors’ Picks. Circ Cardiovasc Imaging 2013. [DOI: 10.1161/circimaging.113.001335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lauritzen MH, Laustsen C, Butt SA, Magnusson P, Søgaard LV, Ardenkjær-Larsen JH, Åkeson P. Enhancing the [13C]bicarbonate signal in cardiac hyperpolarized [1-13C]pyruvate MRS studies by infusion of glucose, insulin and potassium. NMR IN BIOMEDICINE 2013; 26:1496-500. [PMID: 23794521 DOI: 10.1002/nbm.2982] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 05/07/2013] [Accepted: 05/08/2013] [Indexed: 05/07/2023]
Abstract
A change in myocardial metabolism is a known effect of several diseases. MRS with hyperpolarized (13)C-labelled pyruvate is a technique capable of detecting changes in myocardial pyruvate metabolism, and has proven to be useful for the evaluation of myocardial ischaemia in vivo. However, during fasting, the myocardial glucose oxidation is low and the fatty acid oxidation (β-oxidation) is high, which complicates the interpretation of pyruvate metabolism with the technique. The aim of this study was to investigate whether the infusion of glucose, insulin and potassium (GIK) could increase the myocardial glucose oxidation in the citric acid cycle, reflected as an increase in the [(13)C]bicarbonate signal in cardiac hyperpolarized [1-(13)C]pyruvate MRS measurements in fasted rats. Two groups of rats were infused with two different doses of GIK and investigated by MRS after injection of hyperpolarized [1-(13)C]pyruvate. No [(13)C]bicarbonate signal could be detected in the fasted state. However, a significant increase in the [(13)C]bicarbonate signal was observed by the infusion of a high dose of GIK. This study demonstrates that a high [(13)C]bicarbonate signal can be achieved by GIK infusion in fasted rats. The increased [(13)C]bicarbonate signal indicates an increased flux of pyruvate through the pyruvate dehydrogenase enzyme complex and an increase in myocardial glucose oxidation through the citric acid cycle.
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Affiliation(s)
- Mette Hauge Lauritzen
- Danish Research Centre for Magnetic Resonance (DRCMR), Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
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Abstract
The heart has a high rate of ATP production and turnover that is required to maintain its continuous mechanical work. Perturbations in ATP-generating processes may therefore affect contractile function directly. Characterizing cardiac metabolism in heart failure (HF) revealed several metabolic alterations called metabolic remodeling, ranging from changes in substrate use to mitochondrial dysfunction, ultimately resulting in ATP deficiency and impaired contractility. However, ATP depletion is not the only relevant consequence of metabolic remodeling during HF. By providing cellular building blocks and signaling molecules, metabolic pathways control essential processes such as cell growth and regeneration. Thus, alterations in cardiac metabolism may also affect the progression to HF by mechanisms beyond ATP supply. Our aim is therefore to highlight that metabolic remodeling in HF not only results in impaired cardiac energetics but also induces other processes implicated in the development of HF such as structural remodeling and oxidative stress. Accordingly, modulating cardiac metabolism in HF may have significant therapeutic relevance that goes beyond the energetic aspect.
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Affiliation(s)
- Torsten Doenst
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich-Schiller-University Jena, Germany.
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Rider OJ, Tyler DJ. Clinical implications of cardiac hyperpolarized magnetic resonance imaging. J Cardiovasc Magn Reson 2013; 15:93. [PMID: 24103786 PMCID: PMC3819516 DOI: 10.1186/1532-429x-15-93] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/01/2013] [Indexed: 02/01/2023] Open
Abstract
Alterations in cardiac metabolism are now considered a cause, rather than a result, of cardiac disease. Although magnetic resonance spectroscopy has allowed investigation of myocardial energetics, the inherently low sensitivity of the technique has limited its clinical application in the study of cardiac metabolism. The development of a novel hyperpolarization technique, based on the process of dynamic nuclear polarization, when combined with the metabolic tracers [1-(13)C] and [2-(13)C] pyruvate, has resulted in significant advances in the understanding of real time myocardial metabolism in the normal and diseased heart in vivo. This review focuses on the changes in myocardial substrate selection and downstream metabolism of hyperpolarized 13C labelled pyruvate that have been shown in diabetes, ischaemic heart disease, cardiac hypertrophy and heart failure in animal models of disease and how these could translate into clinical practice with the advent of clinical grade hyperpolarizer systems.
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Affiliation(s)
- Oliver J Rider
- University of Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Oxford Metabolic Imaging Group, University of Oxford, Oxford, UK
| | - Damian J Tyler
- Oxford Metabolic Imaging Group, University of Oxford, Oxford, UK
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
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Mori J, Zhang L, Oudit GY, Lopaschuk GD. Impact of the renin–angiotensin system on cardiac energy metabolism in heart failure. J Mol Cell Cardiol 2013; 63:98-106. [DOI: 10.1016/j.yjmcc.2013.07.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 07/12/2013] [Accepted: 07/14/2013] [Indexed: 01/12/2023]
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Ball DR, Rowlands B, Dodd MS, Le Page L, Ball V, Carr CA, Clarke K, Tyler DJ. Hyperpolarized butyrate: a metabolic probe of short chain fatty acid metabolism in the heart. Magn Reson Med 2013; 71:1663-9. [PMID: 23798473 PMCID: PMC4238803 DOI: 10.1002/mrm.24849] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/25/2013] [Accepted: 05/28/2013] [Indexed: 12/13/2022]
Abstract
Purpose Butyrate, a short chain fatty acid, was studied as a novel hyperpolarized substrate for use in dynamic nuclear polarization enhanced magnetic resonance spectroscopy experiments, to define the pathways of short chain fatty acid and ketone body metabolism in real time. Methods Butyrate was polarized via the dynamic nuclear polarization process and subsequently dissolved to generate an injectable metabolic substrate. Metabolism was initially assessed in the isolated perfused rat heart, followed by evaluation in the in vivo rat heart. Results Hyperpolarized butyrate was generated with a polarization level of 7% and was shown to have a T1 relaxation time of 20 s. These physical characteristics were sufficient to enable assessment of multiple steps in its metabolism, with the ketone body acetoacetate and several tricarboxylic acid cycle intermediates observed both in vitro and in vivo. Metabolite to butyrate ratios of 0.1–0.4% and 0.5–2% were observed in vitro and in vivo respectively, similar to levels previously observed with hyperpolarized [2-13C]pyruvate. Conclusions In this study, butyrate has been demonstrated to be a suitable hyperpolarized substrate capable of revealing multi-step metabolism in dynamic nuclear polarization experiments and providing information on the metabolism of fatty acids not currently achievable with other hyperpolarized substrates. Magn Reson Med 71:1663–1669, 2014. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Daniel R Ball
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
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73
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Bastiaansen JAM, Cheng T, Mishkovsky M, Duarte JMN, Comment A, Gruetter R. In vivo enzymatic activity of acetylCoA synthetase in skeletal muscle revealed by (13)C turnover from hyperpolarized [1-(13)C]acetate to [1-(13)C]acetylcarnitine. Biochim Biophys Acta Gen Subj 2013; 1830:4171-8. [PMID: 23545238 DOI: 10.1016/j.bbagen.2013.03.023] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 03/20/2013] [Accepted: 03/22/2013] [Indexed: 12/28/2022]
Abstract
BACKGROUND Acetate metabolism in skeletal muscle is regulated by acetylCoA synthetase (ACS). The main function of ACS is to provide cells with acetylCoA, a key molecule for numerous metabolic pathways including fatty acid and cholesterol synthesis and the Krebs cycle. METHODS Hyperpolarized [1-(13)C]acetate prepared via dissolution dynamic nuclear polarization was injected intravenously at different concentrations into rats. The (13)C magnetic resonance signals of [1-(13)C]acetate and [1-(13)C]acetylcarnitine were recorded in vivo for 1min. The kinetic rate constants related to the transformation of acetate into acetylcarnitine were deduced from the 3s time resolution measurements using two approaches, either mathematical modeling or relative metabolite ratios. RESULTS Although separated by two biochemical transformations, a kinetic analysis of the (13)C label flow from [1-(13)C]acetate to [1-(13)C]acetylcarnitine led to a unique determination of the activity of ACS. The in vivo Michaelis constants for ACS were KM=0.35±0.13mM and Vmax=0.199±0.031μmol/g/min. CONCLUSIONS The conversion rates from hyperpolarized acetate into acetylcarnitine were quantified in vivo and, although separated by two enzymatic reactions, these rates uniquely defined the activity of ACS. The conversion rates associated with ACS were obtained using two analytical approaches, both methods yielding similar results. GENERAL SIGNIFICANCE This study demonstrates the feasibility of directly measuring ACS activity in vivo and, since the activity of ACS can be affected by various pathological states such as cancer or diabetes, the proposed method could be used to non-invasively probe metabolic signatures of ACS in diseased tissue.
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Dodd MS, Ball V, Bray R, Ashrafian H, Watkins H, Clarke K, Tyler DJ. In vivo mouse cardiac hyperpolarized magnetic resonance spectroscopy. J Cardiovasc Magn Reson 2013; 15:19. [PMID: 23414451 PMCID: PMC3599631 DOI: 10.1186/1532-429x-15-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 01/21/2013] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Alterations in cardiac metabolism accompany many diseases of the heart. The advent of cardiac hyperpolarized magnetic resonance spectroscopy (MRS), via dynamic nuclear polarization (DNP), has enabled a greater understanding of the in vivo metabolic changes that occur as a consequence of myocardial infarction, hypertrophy and diabetes. However, all cardiac studies performed to date have focused on rats and larger animals, whereas more information could be gained through the study of transgenic mouse models of heart disease. Translation from the rat to the mouse is challenging, due in part to the reduced heart size (1/10(th)) and the increased heart rate (50%) in the mouse compared to the rat. METHODS AND RESULTS In this study, we have investigated the in vivo metabolism of [1-(13)C]pyruvate in the mouse heart. To demonstrate the sensitivity of the method to detect alterations in pyruvate dehydrogenase (PDH) flux, two well characterised methods of PDH modulation were performed; overnight fasting and infusion of sodium dichloroacetate (DCA). Fasting resulted in an 85% reduction in PDH flux, whilst DCA infusion increased PDH flux by 123%. A comparison of three commonly used control mouse strains was performed revealing significant metabolic differences between strains. CONCLUSIONS We have successfully demonstrated a hyperpolarized DNP protocol to investigate in vivo alterations within the diseased mouse heart. This technique offers a significant advantage over existing in vitro techniques as it reduces animal numbers and decreases biological variability. Thus [1-(13)C]pyruvate can be used to provide an in vivo cardiac metabolic profile of transgenic mice.
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Affiliation(s)
- Michael S Dodd
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Vicky Ball
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
| | - Rosalind Bray
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
| | - Houman Ashrafian
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Kieran Clarke
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
| | - Damian J Tyler
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, UK
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Lee P, Leong W, Tan T, Lim M, Han W, Radda GK. In vivo hyperpolarized carbon-13 magnetic resonance spectroscopy reveals increased pyruvate carboxylase flux in an insulin-resistant mouse model. Hepatology 2013; 57:515-24. [PMID: 22911492 DOI: 10.1002/hep.26028] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 08/08/2012] [Indexed: 01/22/2023]
Abstract
UNLABELLED The pathogenesis of type 2 diabetes is characterized by impaired insulin action and increased hepatic glucose production (HGP). Despite the importance of hepatic metabolic aberrations in diabetes development, there is currently no molecular probe that allows measurement of hepatic gluconeogenic pathways in vivo and in a noninvasive manner. In this study, we used hyperpolarized carbon 13 ((13)C)-labeled pyruvate magnetic resonance spectroscopy (MRS) to determine changes in hepatic gluconeogenesis in a high-fat diet (HFD)-induced mouse model of type 2 diabetes. Compared with mice on chow diet, HFD-fed mice displayed higher levels of oxaloacetate, aspartate, and malate, along with increased (13)C label exchange rates between hyperpolarized [1-(13) C]pyruvate and its downstream metabolites, [1-(13)C]malate and [1-(13)C]aspartate. Biochemical assays using liver extract revealed up-regulated malate dehydrogenase activity, but not aspartate transaminase activity, in HFD-fed mice. Moreover, the (13) C label exchange rate between [1-(13)C]pyruvate and [1-(13)C]aspartate (k(pyr->asp)) exhibited apparent correlation with gluconeogenic pyruvate carboxylase (PC) activity in hepatocytes. Finally, up-regulated HGP by glucagon stimulation was detected by an increase in aspartate signal and k(pyr->asp), whereas HFD mice treated with metformin for 2 weeks displayed lower production of aspartate and malate, as well as reduced k(pyr->asp) and (13)C-label exchange rate between pyruvate and malate, consistent with down-regulated gluconeogenesis. CONCLUSION Taken together, we demonstrate that increased PC flux is an important pathway responsible for increased HGP in diabetes development, and that pharmacologically induced metabolic changes specific to the liver can be detected in vivo with a hyperpolarized (13)C-biomolecular probe. Hyperpolarized (13)C MRS and the determination of metabolite exchange rates may allow longitudinal monitoring of liver function in disease development.
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Affiliation(s)
- Philip Lee
- Singapore Bioimaging Consortium, Singapore.
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Yin X, Dwyer J, Langley SR, Mayr U, Xing Q, Drozdov I, Nabeebaccus A, Shah AM, Madhu B, Griffiths J, Edwards LM, Mayr M. Effects of perhexiline-induced fuel switch on the cardiac proteome and metabolome. J Mol Cell Cardiol 2012; 55:27-30. [PMID: 23277191 PMCID: PMC3573230 DOI: 10.1016/j.yjmcc.2012.12.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/01/2012] [Accepted: 12/14/2012] [Indexed: 11/24/2022]
Abstract
Perhexiline is a potent anti-anginal drug used for treatment of refractory angina and other forms of heart disease. It provides an oxygen sparing effect in the myocardium by creating a switch from fatty acid to glucose metabolism through partial inhibition of carnitine palmitoyltransferase 1 and 2. However, the precise molecular mechanisms underlying the cardioprotective effects elicited by perhexiline are not fully understood. The present study employed a combined proteomics, metabolomics and computational approach to characterise changes in murine hearts upon treatment with perhexiline. According to results based on difference in-gel electrophoresis, the most profound change in the cardiac proteome related to the activation of the pyruvate dehydrogenase complex. Metabolomic analysis by high-resolution nuclear magnetic resonance spectroscopy showed lower levels of total creatine and taurine in hearts of perhexiline-treated mice. Creatine and taurine levels were also significantly correlated in a cross-correlation analysis of all metabolites. Computational modelling suggested that far from inducing a simple shift from fatty acid to glucose oxidation, perhexiline may cause complex rebalancing of carbon and nucleotide phosphate fluxes, fuelled by increased lactate and amino acid uptake, to increase metabolic flexibility and to maintain cardiac output. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism".
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Affiliation(s)
- Xiaoke Yin
- King's BHF Centre, King's College London, UK
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Schroeder MA, Lau AZ, Chen AP, Gu Y, Nagendran J, Barry J, Hu X, Dyck JRB, Tyler DJ, Clarke K, Connelly KA, Wright GA, Cunningham CH. Hyperpolarized (13)C magnetic resonance reveals early- and late-onset changes to in vivo pyruvate metabolism in the failing heart. Eur J Heart Fail 2012; 15:130-40. [PMID: 23258802 PMCID: PMC3547367 DOI: 10.1093/eurjhf/hfs192] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Aims Impaired energy metabolism has been implicated in the pathogenesis of heart failure. Hyperpolarized 13C magnetic resonance (MR), in which 13C-labelled metabolites are followed using MR imaging (MRI) or spectroscopy (MRS), has enabled non-invasive assessment of pyruvate metabolism. We investigated the hypothesis that if we serially examined a model of heart failure using non-invasive hyperpolarized [13C]pyruvate with MR, the profile of in vivo pyruvate oxidation would change throughout the course of the disease. Methods and results Dilated cardiomyopathy (DCM) was induced in pigs (n = 5) by rapid pacing. Pigs were examined using MR at weekly time points: cine-MRI assessed cardiac structure and function; hyperpolarized [2-13C]pyruvate was administered intravenously, and 13C MRS monitored [13C]glutamate production; 31P MRS assessed cardiac energetics [phosphocreatine (PCr)/ATP]; and hyperpolarized [1-13C]pyruvate was administered for MRI of pyruvate dehydrogenase complex (PDC)-mediated pyruvate oxidation via [13C]bicarbonate production. Early in pacing, the cardiac index decreased by 25%, PCr/ATP decreased by 26%, and [13C]glutamate production decreased by 51%. After clinical features of DCM appeared, end-diastolic volume increased by 40% and [13C]bicarbonate production decreased by 67%. Pyruvate dehydrogenase kinase 4 protein increased by two-fold, and phosphorylated Akt decreased by half. Peroxisome proliferator-activated receptor-α and carnitine palmitoyltransferase-1 gene expression decreased by a half and a third, respectively. Conclusion Despite early changes associated with cardiac energetics and 13C incorporation into the Krebs cycle, pyruvate oxidation was maintained until DCM developed, when the heart's capacity to oxidize both pyruvate and fats was reduced. Hyperpolarized 13C MR may be important to characterize metabolic changes that occur during heart failure progression.
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Affiliation(s)
- Marie A Schroeder
- Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Room M326A, Toronto, Ontario M4N 3M5, Canada.
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Dodd MS, Ball DR, Schroeder MA, Le Page LM, Atherton HJ, Heather LC, Seymour AM, Ashrafian H, Watkins H, Clarke K, Tyler DJ. In vivo alterations in cardiac metabolism and function in the spontaneously hypertensive rat heart. Cardiovasc Res 2012; 95:69-76. [PMID: 22593200 PMCID: PMC4617603 DOI: 10.1093/cvr/cvs164] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS The aim of this work was to use hyperpolarized carbon-13 ((13)C) magnetic resonance (MR) spectroscopy and cine MR imaging (MRI) to assess in vivo cardiac metabolism and function in the 15-week-old spontaneously hypertensive rat (SHR) heart. At this time point, the SHR displays hypertension and concentric hypertrophy. One of the cellular adaptations to hypertrophy is a reduction in β-oxidation, and it has previously been shown that in response to hypertrophy the SHR heart switches to a glycolytic/glucose-oxidative phenotype. METHODS AND RESULTS Cine-MRI (magnetic resonance imaging) was used to assess cardiac function and degree of cardiac hypertrophy. Wistar rats were used as controls. SHRs displayed functional changes in stroke volume, heart rate, and late peak-diastolic filling alongside significant hypertrophy (a 56% increase in left ventricular mass). Using hyperpolarized [1-(13)C] and [2-(13)C]pyruvate, an 85% increase in (13)C label flux through pyruvate dehydrogenase (PDH) was seen in the SHR heart and (13)C label incorporation into citrate, acetylcarnitine, and glutamate pools was elevated in proportion to the increase in PDH flux. These findings were confirmed using biochemical analysis of PDH activity and protein expression of PDH regulatory enzymes. CONCLUSIONS Functional and structural alterations in the SHR heart are consistent with the hypertrophied phenotype. Our in vivo work indicates a preference for glucose metabolism in the SHR heart, a move away from predominantly fatty acid oxidative metabolism. Interestingly, (13)C label flux into lactate was unchanged, indicating no switch to an anaerobic glycolytic phenotype, but rather an increased reliance on glucose oxidation in the SHR heart.
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Affiliation(s)
- Michael S Dodd
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Parks Road, Oxford, UK
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79
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Balschi JA. In vivo clinical measures of intermediary metabolism are inadequate: can a new magnetic resonance spectroscopy technology do better? Circ Cardiovasc Imaging 2012; 5:171-4. [PMID: 22438422 DOI: 10.1161/circimaging.111.972240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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80
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Schroeder MA, Atherton HJ, Dodd MS, Lee P, Cochlin LE, Radda GK, Clarke K, Tyler DJ. The cycling of acetyl-coenzyme A through acetylcarnitine buffers cardiac substrate supply: a hyperpolarized 13C magnetic resonance study. Circ Cardiovasc Imaging 2012. [PMID: 22238215 DOI: 10.1161/circimaging.111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND Carnitine acetyltransferase catalyzes the reversible conversion of acetyl-coenzyme A (CoA) into acetylcarnitine. The aim of this study was to use the metabolic tracer hyperpolarized [2-(13)C]pyruvate with magnetic resonance spectroscopy to determine whether carnitine acetyltransferase facilitates carbohydrate oxidation in the heart. METHODS AND RESULTS Ex vivo, following hyperpolarized [2-(13)C]pyruvate infusion, the [1-(13)C]acetylcarnitine resonance was saturated with a radiofrequency pulse, and the effect of this saturation on [1-(13)C]citrate and [5-(13)C]glutamate was observed. In vivo, [2-(13)C]pyruvate was infused into 3 groups of fed male Wistar rats: (1) controls, (2) rats in which dichloroacetate enhanced pyruvate dehydrogenase flux, and (3) rats in which dobutamine elevated cardiac workload. In the perfused heart, [1-(13)C]acetylcarnitine saturation reduced the [1-(13)C]citrate and [5-(13)C]glutamate resonances by 63% and 51%, respectively, indicating a rapid exchange between pyruvate-derived acetyl-CoA and the acetylcarnitine pool. In vivo, dichloroacetate increased the rate of [1-(13)C]acetylcarnitine production by 35% and increased the overall acetylcarnitine pool size by 33%. Dobutamine decreased the rate of [1-(13)C]acetylcarnitine production by 37% and decreased the acetylcarnitine pool size by 40%. CONCLUSIONS Hyperpolarized (13)C magnetic resonance spectroscopy has revealed that acetylcarnitine provides a route of disposal for excess acetyl-CoA and a means to replenish acetyl-CoA when cardiac workload is increased. Cycling of acetyl-CoA through acetylcarnitine appears key to matching instantaneous acetyl-CoA supply with metabolic demand, thereby helping to balance myocardial substrate supply and contractile function.
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Affiliation(s)
- Marie A Schroeder
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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81
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Circulation: Cardiovascular Imaging
Editors' Picks. Circ Cardiovasc Imaging 2012. [DOI: 10.1161/circimaging.112.974097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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82
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Cardiovascular Magnetic Resonance of Myocardial Structure, Function, and Perfusion in Mouse and Rat Models. CURRENT CARDIOVASCULAR IMAGING REPORTS 2012. [DOI: 10.1007/s12410-012-9122-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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83
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Schroeder MA, Atherton HJ, Dodd MS, Lee P, Cochlin LE, Radda GK, Clarke K, Tyler DJ. The cycling of acetyl-coenzyme A through acetylcarnitine buffers cardiac substrate supply: a hyperpolarized 13C magnetic resonance study. Circ Cardiovasc Imaging 2012; 5:201-9. [PMID: 22238215 DOI: 10.1161/circimaging.111.969451] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Carnitine acetyltransferase catalyzes the reversible conversion of acetyl-coenzyme A (CoA) into acetylcarnitine. The aim of this study was to use the metabolic tracer hyperpolarized [2-(13)C]pyruvate with magnetic resonance spectroscopy to determine whether carnitine acetyltransferase facilitates carbohydrate oxidation in the heart. METHODS AND RESULTS Ex vivo, following hyperpolarized [2-(13)C]pyruvate infusion, the [1-(13)C]acetylcarnitine resonance was saturated with a radiofrequency pulse, and the effect of this saturation on [1-(13)C]citrate and [5-(13)C]glutamate was observed. In vivo, [2-(13)C]pyruvate was infused into 3 groups of fed male Wistar rats: (1) controls, (2) rats in which dichloroacetate enhanced pyruvate dehydrogenase flux, and (3) rats in which dobutamine elevated cardiac workload. In the perfused heart, [1-(13)C]acetylcarnitine saturation reduced the [1-(13)C]citrate and [5-(13)C]glutamate resonances by 63% and 51%, respectively, indicating a rapid exchange between pyruvate-derived acetyl-CoA and the acetylcarnitine pool. In vivo, dichloroacetate increased the rate of [1-(13)C]acetylcarnitine production by 35% and increased the overall acetylcarnitine pool size by 33%. Dobutamine decreased the rate of [1-(13)C]acetylcarnitine production by 37% and decreased the acetylcarnitine pool size by 40%. CONCLUSIONS Hyperpolarized (13)C magnetic resonance spectroscopy has revealed that acetylcarnitine provides a route of disposal for excess acetyl-CoA and a means to replenish acetyl-CoA when cardiac workload is increased. Cycling of acetyl-CoA through acetylcarnitine appears key to matching instantaneous acetyl-CoA supply with metabolic demand, thereby helping to balance myocardial substrate supply and contractile function.
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Affiliation(s)
- Marie A Schroeder
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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84
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Kociol RD. Circulation: Heart Failure
Editors' Picks: Most Important Papers in Heart Failure and Imaging. Circ Heart Fail 2012. [DOI: 10.1161/circheartfailure.111.966176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The following are highlights from
Circulation: Heart Failure
Topic Review. This series will summarize the most important manuscripts, as selected by the editors, that have been published in the
Circulation
portfolio. The objective of this series is to provide our readership with a timely comprehensive selection of important papers that are relevant to the heart failure audience. The studies included in this article represent the most noteworthy research in the areas of heart failure and imaging.
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Schroeder MA, Clarke K, Neubauer S, Tyler DJ. Hyperpolarized magnetic resonance: a novel technique for the in vivo assessment of cardiovascular disease. Circulation 2011; 124:1580-94. [PMID: 21969318 DOI: 10.1161/circulationaha.111.024919] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Marie A Schroeder
- Department of Physiology, Anatomy, and Genetics, Sherrington Bldg, University of Oxford, Parks Rd, Oxford, UK OX1 3PT
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