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Widmaier M, Lim SI, Wenz D, Xin L. Fast in vivo assay of creatine kinase activity in the human brain by 31 P magnetic resonance fingerprinting. NMR IN BIOMEDICINE 2023; 36:e4998. [PMID: 37424110 DOI: 10.1002/nbm.4998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 05/15/2023] [Accepted: 06/12/2023] [Indexed: 07/11/2023]
Abstract
A new and efficient magnetisation transfer 31 P magnetic resonance fingerprinting (MT-31 P-MRF) approach is introduced to measure the creatine kinase metabolic ratek CK between phosphocreatine (PCr) and adenosine triphosphate (ATP) in human brain. The MRF framework is extended to overcome challenges in conventional 31 P measurement methods in the human brain, enabling reduced acquisition time and specific absorption rate (SAR). To address the challenge of creating and matching large multiparametric dictionaries in an MRF scheme, a nested iteration interpolation method (NIIM) is introduced. As the number of parameters to estimate increases, the size of the dictionary grows exponentially. NIIM can reduce the computational load by breaking dictionary matching into subsolutions of linear computational order. MT-31 P-MRF combined with NIIM providesT 1 PCr ,T 1 ATP andk CK estimates in good agreement with those obtained by the exchange kinetics by band inversion transfer (EBIT) method and literature values. Furthermore, the test-retest reproducibility results showed that MT-31 P-MRF achieves a similar or better coefficient of variation (<12%) forT 1 ATP andk CK measurements in 4 min 15 s, than EBIT with 17 min 4 s scan time, enabling a fourfold reduction in scan time. We conclude that MT-31 P-MRF in combination with NIIM is a fast, accurate, and reproducible approach for in vivok CK assays in the human brain, which enables the potential to investigate energy metabolism in a clinical setting.
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Affiliation(s)
- Mark Widmaier
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Laboratory for Functional and Metabolic Imaging, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
- Animal Imaging and Technology, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - Song-I Lim
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Laboratory for Functional and Metabolic Imaging, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
- Animal Imaging and Technology, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - Daniel Wenz
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
| | - Lijing Xin
- CIBM Center for Biomedical Imaging, Lausanne, Switzerland
- Animal Imaging and Technology, École polytechnique fédérale de Lausanne, Lausanne, Switzerland
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2
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Fear EJ, Torkelsen FH, Zamboni E, Chen K, Scott M, Jeffery G, Baseler H, Kennerley AJ. Use of 31 P magnetisation transfer magnetic resonance spectroscopy to measure ATP changes after 670 nm transcranial photobiomodulation in older adults. Aging Cell 2023; 22:e14005. [PMID: 37803929 PMCID: PMC10652330 DOI: 10.1111/acel.14005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/18/2023] [Accepted: 09/22/2023] [Indexed: 10/08/2023] Open
Abstract
Mitochondrial function declines with age, and many pathological processes in neurodegenerative diseases stem from this dysfunction when mitochondria fail to produce the necessary energy required. Photobiomodulation (PBM), long-wavelength light therapy, has been shown to rescue mitochondrial function in animal models and improve human health, but clinical uptake is limited due to uncertainty around efficacy and the mechanisms responsible. Using 31 P magnetisation transfer magnetic resonance spectroscopy (MT-MRS) we quantify, for the first time, the effects of 670 nm PBM treatment on healthy ageing human brains. We find a significant increase in the rate of ATP synthase flux in the brain after PBM in a cohort of older adults. Our study provides initial evidence of PBM therapeutic efficacy for improving mitochondrial function and restoring ATP flux with age, but recognises that wider studies are now required to confirm any resultant cognitive benefits.
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Affiliation(s)
- Elizabeth J. Fear
- Hull York Medical SchoolUniversity of YorkYorkUK
- Department of Biomolecular SciencesUniversity of Urbino Carlo BoUrbinoItaly
| | | | - Elisa Zamboni
- Department of PsychologyUniversity of YorkYorkUK
- School of PsychologyUniversity of NottinghamNottinghamUK
| | | | - Martin Scott
- Department of PsychologyUniversity of YorkYorkUK
- Department of PsychologyStanford UniversityStanfordCaliforniaUSA
| | - Glenn Jeffery
- Faculty of Brain SciencesInstitute of Ophthalmology, UCLLondonUK
| | - Heidi Baseler
- Hull York Medical SchoolUniversity of YorkYorkUK
- Department of PsychologyUniversity of YorkYorkUK
| | - Aneurin J. Kennerley
- Department of ChemistryUniversity of YorkYorkUK
- Institute of SportManchester Metropolitan UniversityManchesterUK
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3
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Zapata Bustos R, Coletta DK, Galons JP, Davidson LB, Langlais PR, Funk JL, Willis WT, Mandarino LJ. Nonequilibrium thermodynamics and mitochondrial protein content predict insulin sensitivity and fuel selection during exercise in human skeletal muscle. Front Physiol 2023; 14:1208186. [PMID: 37485059 PMCID: PMC10361819 DOI: 10.3389/fphys.2023.1208186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/16/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction: Many investigators have attempted to define the molecular nature of changes responsible for insulin resistance in muscle, but a molecular approach may not consider the overall physiological context of muscle. Because the energetic state of ATP (ΔGATP) could affect the rate of insulin-stimulated, energy-consuming processes, the present study was undertaken to determine whether the thermodynamic state of skeletal muscle can partially explain insulin sensitivity and fuel selection independently of molecular changes. Methods: 31P-MRS was used with glucose clamps, exercise studies, muscle biopsies and proteomics to measure insulin sensitivity, thermodynamic variables, mitochondrial protein content, and aerobic capacity in 16 volunteers. Results: After showing calibrated 31P-MRS measurements conformed to a linear electrical circuit model of muscle nonequilibrium thermodynamics, we used these measurements in multiple stepwise regression against rates of insulin-stimulated glucose disposal and fuel oxidation. Multiple linear regression analyses showed 53% of the variance in insulin sensitivity was explained by 1) VO2max (p = 0.001) and the 2) slope of the relationship of ΔGATP with the rate of oxidative phosphorylation (p = 0.007). This slope represents conductance in the linear model (functional content of mitochondria). Mitochondrial protein content from proteomics was an independent predictor of fractional fat oxidation during mild exercise (R2 = 0.55, p = 0.001). Conclusion: Higher mitochondrial functional content is related to the ability of skeletal muscle to maintain a greater ΔGATP, which may lead to faster rates of insulin-stimulated processes. Mitochondrial protein content per se can explain fractional fat oxidation during mild exercise.
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Affiliation(s)
- Rocio Zapata Bustos
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Dawn K. Coletta
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
- Department of Physiology, The University of Arizona, Tucson, AZ, United States
| | - Jean-Philippe Galons
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States
| | - Lisa B. Davidson
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Paul R. Langlais
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Janet L. Funk
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Wayne T. Willis
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Lawrence J. Mandarino
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
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4
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Vassallo G, Garello F, Aime S, Terreno E, Delli Castelli D. 31P ParaCEST: 31P MRI-CEST Imaging Based on the Formation of a Ternary Adduct between Inorganic Phosphate and Eu-DO3A. Inorg Chem 2022; 61:19663-19667. [PMID: 36445702 PMCID: PMC9946289 DOI: 10.1021/acs.inorgchem.2c03329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Development of the field of magnetic resonance imaging (MRI) chemical exchange saturation transfer (CEST) contrast agents is hampered by the limited sensitivity of the technique. In water, the high proton concentration allows for an enormous amplification of the exchanging proton pool. However, the 1H CEST in water implies that the number of nuclear spins of the CEST-generating species has to be in the millimolar range. The use of nuclei other than a proton allows exploitation of signals different from that of water, thus lowering the concentration of the exchanging pool as the source of the CEST effect. In this work, we report on the detection of a 31P signal from endogenous inorganic phosphate (Pifree) as the source of CEST contrast by promoting its exchange with the Pi bound to the exogenous complex 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (Pibound). The herein-reported results demonstrate that this approach can improve the detectability threshold by 3 orders of magnitude with respect to the conventional 1H CEST detection (considered per single proton). This achievement reflects the decrease of the bulk concentration of the detected signal from 111.2 M (water) to 10 mM (Pi). This method paves the way to a number of biological studies and clinically translatable applications, herein addressed with a proof-of-concept in the field of cellular imaging.
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Affiliation(s)
- Giulia Vassallo
- Department
of Molecular Biotechnology and Health Science, University of Turin, Via Nizza 52, 10126Turin, Italy
| | - Francesca Garello
- Department
of Molecular Biotechnology and Health Science, University of Turin, Via Nizza 52, 10126Turin, Italy
| | - Silvio Aime
- IRCCS
SDN SynLab, Via E. Gianturco
113, 80143Napoli, Italy
| | - Enzo Terreno
- Department
of Molecular Biotechnology and Health Science, University of Turin, Via Nizza 52, 10126Turin, Italy
| | - Daniela Delli Castelli
- Department
of Molecular Biotechnology and Health Science, University of Turin, Via Nizza 52, 10126Turin, Italy,. Phone: +39-0116706493
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5
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Demetriou E, Kujawa A, Golay X. Pulse sequences for measuring exchange rates between proton species: From unlocalised NMR spectroscopy to chemical exchange saturation transfer imaging. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 120-121:25-71. [PMID: 33198968 DOI: 10.1016/j.pnmrs.2020.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 06/27/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Within the field of NMR spectroscopy, the study of chemical exchange processes through saturation transfer techniques has a long history. In the context of MRI, chemical exchange techniques have been adapted to increase the sensitivity of imaging to small fractions of exchangeable protons, including the labile protons of amines, amides and hydroxyls. The MR contrast is generated by frequency-selective irradiation of the labile protons, which results in a reduction of the water signal associated with transfer of the labile protons' saturated magnetization to the protons of the surrounding free water. The signal intensity depends on the rate of chemical exchange and the concentration of labile protons as well as on the properties of the irradiation field. This methodology is referred to as CEST (chemical exchange saturation transfer) imaging. Applications of CEST include imaging of molecules with short transverse relaxation times and mapping of physiological parameters such as pH, temperature, buffer concentration and chemical composition due to the dependency of this chemical exchange effect on all these parameters. This article aims to describe these effects both theoretically and experimentally. In depth analysis and mathematical modelling are provided for all pulse sequences designed to date to measure the chemical exchange rate. Importantly, it has become clear that the background signal from semi-solid protons and the presence of the Nuclear Overhauser Effect (NOE), either through direct dipole-dipole mechanisms or through exchange-relayed signals, complicates the analysis of CEST effects. Therefore, advanced methods to suppress these confounding factors have been developed, and these are also reviewed. Finally, the experimental work conducted both in vitro and in vivo is discussed and the progress of CEST imaging towards clinical practice is presented.
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Affiliation(s)
- Eleni Demetriou
- Brain Repair & Rehabilitation, Institute of Neurology, University College London, United Kingdom.
| | - Aaron Kujawa
- Brain Repair & Rehabilitation, Institute of Neurology, University College London, United Kingdom.
| | - Xavier Golay
- Brain Repair & Rehabilitation, Institute of Neurology, University College London, United Kingdom.
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6
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Krumpolec P, Klepochová R, Just I, Tušek Jelenc M, Frollo I, Ukropec J, Ukropcová B, Trattnig S, Krššák M, Valkovič L. Multinuclear MRS at 7T Uncovers Exercise Driven Differences in Skeletal Muscle Energy Metabolism Between Young and Seniors. Front Physiol 2020; 11:644. [PMID: 32695010 PMCID: PMC7336536 DOI: 10.3389/fphys.2020.00644] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 05/20/2020] [Indexed: 12/27/2022] Open
Abstract
Purpose: Aging is associated with changes in muscle energy metabolism. Proton (1H) and phosphorous (31P) magnetic resonance spectroscopy (MRS) has been successfully applied for non-invasive investigation of skeletal muscle metabolism. The aim of this study was to detect differences in adenosine triphosphate (ATP) production in the aging muscle by 31P-MRS and to identify potential changes associated with buffer capacity of muscle carnosine by 1H-MRS. Methods: Fifteen young and nineteen elderly volunteers were examined. 1H and 31P-MRS spectra were acquired at high field (7T). The investigation included carnosine quantification using 1H-MRS and resting and dynamic 31P-MRS, both including saturation transfer measurements of phosphocreatine (PCr), and inorganic phosphate (Pi)-to-ATP metabolic fluxes. Results: Elderly volunteers had higher time constant of PCr recovery (τPCr) in comparison to the young volunteers. Exercise was connected with significant decrease in PCr-to-ATP flux in both groups. Moreover, PCr-to-ATP flux was significantly higher in young compared to elderly both at rest and during exercise. Similarly, an increment of Pi-to-ATP flux with exercise was found in both groups but the intergroup difference was only observed during exercise. Elderly had lower muscle carnosine concentration and lower postexercise pH. A strong increase in phosphomonoester (PME) concentration was observed with exercise in elderly, and a faster Pi:PCr kinetics was found in young volunteers compared to elderly during the recovery period. Conclusion: Observations of a massive increment of PME concentration together with high Pi-to-ATP flux during exercise in seniors refer to decreased ability of the muscle to meet the metabolic requirements of exercise and thus a limited ability of seniors to effectively support the exercise load.
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Affiliation(s)
- Patrik Krumpolec
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.,Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Radka Klepochová
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Ivica Just
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Marjeta Tušek Jelenc
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Ivan Frollo
- Department of Imaging Methods, Institute of Measurements Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jozef Ukropec
- Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Barbara Ukropcová
- Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovakia.,Faculty of Medicine, Institute of Pathophysiology, Comenius University in Bratislava, Bratislava, Slovakia
| | - Siegfried Trattnig
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria
| | - Martin Krššák
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria.,Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Ladislav Valkovič
- High Field MR Center, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.,Department of Imaging Methods, Institute of Measurements Science, Slovak Academy of Sciences, Bratislava, Slovakia.,Oxford Centre for Clinical Magnetic Resonance Research, RDM Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom
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7
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Meyerspeer M, Boesch C, Cameron D, Dezortová M, Forbes SC, Heerschap A, Jeneson JA, Kan HE, Kent J, Layec G, Prompers JJ, Reyngoudt H, Sleigh A, Valkovič L, Kemp GJ. 31 P magnetic resonance spectroscopy in skeletal muscle: Experts' consensus recommendations. NMR IN BIOMEDICINE 2020; 34:e4246. [PMID: 32037688 PMCID: PMC8243949 DOI: 10.1002/nbm.4246] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 12/01/2019] [Accepted: 12/02/2019] [Indexed: 05/07/2023]
Abstract
Skeletal muscle phosphorus-31 31 P MRS is the oldest MRS methodology to be applied to in vivo metabolic research. The technical requirements of 31 P MRS in skeletal muscle depend on the research question, and to assess those questions requires understanding both the relevant muscle physiology, and how 31 P MRS methods can probe it. Here we consider basic signal-acquisition parameters related to radio frequency excitation, TR, TE, spectral resolution, shim and localisation. We make specific recommendations for studies of resting and exercising muscle, including magnetisation transfer, and for data processing. We summarise the metabolic information that can be quantitatively assessed with 31 P MRS, either measured directly or derived by calculations that depend on particular metabolic models, and we give advice on potential problems of interpretation. We give expected values and tolerable ranges for some measured quantities, and minimum requirements for reporting acquisition parameters and experimental results in publications. Reliable examination depends on a reproducible setup, standardised preconditioning of the subject, and careful control of potential difficulties, and we summarise some important considerations and potential confounders. Our recommendations include the quantification and standardisation of contraction intensity, and how best to account for heterogeneous muscle recruitment. We highlight some pitfalls in the assessment of mitochondrial function by analysis of phosphocreatine (PCr) recovery kinetics. Finally, we outline how complementary techniques (near-infrared spectroscopy, arterial spin labelling, BOLD and various other MRI and 1 H MRS measurements) can help in the physiological/metabolic interpretation of 31 P MRS studies by providing information about blood flow and oxygen delivery/utilisation. Our recommendations will assist in achieving the fullest possible reliable picture of muscle physiology and pathophysiology.
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Affiliation(s)
- Martin Meyerspeer
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- High Field MR CenterMedical University of ViennaViennaAustria
| | - Chris Boesch
- DBMR and DIPRUniversity and InselspitalBernSwitzerland
| | - Donnie Cameron
- Norwich Medical SchoolUniversity of East AngliaNorwichUK
- C. J. Gorter Center for High Field MRI, Department of RadiologyLeiden University Medical CentreLeidenthe Netherlands
| | - Monika Dezortová
- MR‐Unit, Department of Diagnostic and Interventional RadiologyInstitute for Clinical and Experimental MedicinePragueCzech Republic
| | - Sean C. Forbes
- Department of Physical TherapyUniversity of FloridaGainesvilleFloridaUSA
| | - Arend Heerschap
- Department of Radiology and Nuclear MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Jeroen A.L. Jeneson
- Department of RadiologyAmsterdam University Medical Center|site AMCAmsterdamthe Netherlands
- Cognitive Neuroscience CenterUniversity Medical Center GroningenGroningenthe Netherlands
- Center for Child Development and Exercise, Wilhelmina Children's HospitalUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Hermien E. Kan
- C. J. Gorter Center for High Field MRI, Department of RadiologyLeiden University Medical CentreLeidenthe Netherlands
- Duchenne CenterThe Netherlands
| | - Jane Kent
- Department of KinesiologyUniversity of Massachusetts AmherstMAUSA
| | - Gwenaël Layec
- Department of KinesiologyUniversity of Massachusetts AmherstMAUSA
- Institute for Applied Life SciencesUniversity of MassachusettsAmherstMAUSA
| | | | - Harmen Reyngoudt
- NMR Laboratory, Neuromuscular Investigation CenterInstitute of Myology AIM‐CEAParisFrance
| | - Alison Sleigh
- Wolfson Brain Imaging CentreUniversity of CambridgeCambridgeUK
- Wellcome Trust‐MRC Institute of Metabolic ScienceUniversity of CambridgeCambridgeUK
- NIHR/Wellcome Trust Clinical Research FacilityCambridge University Hospitals NHS Foundation TrustCambridgeUK
| | - Ladislav Valkovič
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), RDM Cardiovascular Medicine, BHF Centre of Research ExcellenceUniversity of OxfordOxfordUK
- Department of Imaging MethodsInstitute of Measurement Science, Slovak Academy of SciencesBratislavaSlovakia
| | - Graham J. Kemp
- Department of Musculoskeletal Biology and Liverpool Magnetic Resonance Imaging Centre (LiMRIC)University of LiverpoolLiverpoolUK
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8
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Ren J, Sherry AD, Malloy CR. Modular 31 P wideband inversion transfer for integrative analysis of adenosine triphosphate metabolism, T 1 relaxation and molecular dynamics in skeletal muscle at 7T. Magn Reson Med 2019; 81:3440-3452. [PMID: 30793793 DOI: 10.1002/mrm.27686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 01/16/2019] [Accepted: 01/18/2019] [Indexed: 12/13/2022]
Abstract
PURPOSE For efficient and integrative analysis of de novo adenosine triphosphate (ATP) synthesis, creatine-kinase-mediated ATP synthesis, T1 relaxation time, and ATP molecular motion dynamics in human skeletal muscle at rest. METHODS Four inversion-transfer modules differing in center inversion frequency were combined to generate amplified magnetization transfer (MT) effects in targeted MT pathways, including Pi ↔ γ-ATP, PCr ↔ γ-ATP, and 31 Pγ(α)ATP ↔ 31 PβATP . MT effects from both forward and reverse exchange kinetic pathways were acquired to reduce potential bias and confounding factors in integrated data analysis. RESULTS Kinetic data collected using 4 wideband inversion modules (8 minutes each) yielded the forward exchange rate constants, kPCr →γ ATP = 0.31 ± 0.05 s-1 and kPi →γ ATP = 0.064 ± 0.012 s-1 , and the reverse exchange rate constants, kγATP→Pi = 0.034 ± 0.006 s-1 and kγATP→PCr = 1.37 ± 0.22 s-1 , respectively. The cross-relaxation rate constant, σγ(α) ↔ βATP was -0.20 ± 0.03 s-1 , corresponding to ATP rotational correlation time τc of 0.8 ± 0.1 × 10-7 seconds. The intrinsic T1 relaxation times were Pi (9.2 ± 1.4 seconds), PCr (6.2 ± 0.4 seconds), γ-ATP (1.8 ± 0.1 seconds), α-ATP (1.4 ± 0.1 seconds), and β-ATP (1.1 ± 0.1 seconds). Muscle ATP T1 values were found to be significantly longer than those previously measured in the brain using a similar method. CONCLUSION A combination of multiple inversion transfer modules provides a comprehensive and integrated analysis of ATP metabolism and molecular motion dynamics. This relatively fast technique could be potentially useful for studying metabolic disorders in skeletal muscle.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Radiology, 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
| | - 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.,VA North Texas Health Care System, Dallas, Texas
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9
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Klepochová R, Valkovič L, Hochwartner T, Triska C, Bachl N, Tschan H, Trattnig S, Krebs M, Krššák M. Differences in Muscle Metabolism Between Triathletes and Normally Active Volunteers Investigated Using Multinuclear Magnetic Resonance Spectroscopy at 7T. Front Physiol 2018; 9:300. [PMID: 29666584 PMCID: PMC5891578 DOI: 10.3389/fphys.2018.00300] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 03/13/2018] [Indexed: 11/29/2022] Open
Abstract
Purpose: The influence of endurance training on skeletal muscle metabolism can currently be studied only by invasive sampling or through a few related parameters that are investigated by either proton (1H) or phosphorus (31P) magnetic resonance spectroscopy (MRS). The aim of this study was to compare the metabolic differences between endurance-trained triathletes and healthy volunteers using multi-parametric data acquired by both, 31P- and 1H-MRS, at ultra-high field (7T) in a single experimental protocol. This study also aimed to determine the interrelations between these MRS-derived metabolic parameters. Methods: Thirteen male triathletes and ten active male volunteers participated in the study. Proton MRS data from the vastus lateralis yielded concentrations of acetylcarnitine, carnosine, and intramyocellular lipids (IMCL). For the measurement of phosphodiesters (PDEs), inorganic phosphate (Pi), phosphocreatine (PCr), and maximal oxidative capacity (Qmax) phosphorus MRS data were acquired at rest, during 6 min of submaximal exercise and following immediate recovery. Results: The triathletes exhibited significantly higher IMCL levels, higher initial rate of PCr resynthesis (VPCr) during the recovery period, a shorter PCr recovery time constant (τPCr), and higher Qmax. Multivariate stepwise regression analysis identified PDE as the strongest independent predictor of whole-body maximal oxygen uptake (VO2max). Conclusion: In conclusion, we cannot suggest a single MRS-based parameter as an exclusive biomarker of muscular fitness and training status. There is, rather, a combination of different parameters, assessable during a single multi-nuclear MRS session that could be useful for further cross-sectional and/or focused interventional studies on skeletal muscle fitness and training effects.
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Affiliation(s)
- Radka Klepochová
- Department of Biomedical Imaging and Image-Guided Therapy, High-Field MR Center, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MR Imaging, MOLIMA, Vienna, Austria
| | - Ladislav Valkovič
- Oxford Centre for Clinical Magnetic Resonance Research, BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom.,Department of Imaging Methods, Institute of Measurements Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Thomas Hochwartner
- Centre of Sport Science and University Sport, University of Vienna, Vienna, Austria
| | - Christoph Triska
- Centre of Sport Science and University Sport, University of Vienna, Vienna, Austria
| | - Norbert Bachl
- Centre of Sport Science and University Sport, University of Vienna, Vienna, Austria
| | - Harald Tschan
- Centre of Sport Science and University Sport, University of Vienna, Vienna, Austria
| | - Siegfried Trattnig
- Department of Biomedical Imaging and Image-Guided Therapy, High-Field MR Center, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MR Imaging, MOLIMA, Vienna, Austria
| | - Michael Krebs
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Martin Krššák
- Department of Biomedical Imaging and Image-Guided Therapy, High-Field MR Center, Medical University of Vienna, Vienna, Austria.,Christian Doppler Laboratory for Clinical Molecular MR Imaging, MOLIMA, Vienna, Austria.,Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
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10
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Liu Y, Gu Y, Yu X. Assessing tissue metabolism by phosphorous-31 magnetic resonance spectroscopy and imaging: a methodology review. Quant Imaging Med Surg 2017; 7:707-726. [PMID: 29312876 PMCID: PMC5756783 DOI: 10.21037/qims.2017.11.03] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/11/2017] [Indexed: 01/11/2023]
Abstract
Many human diseases are caused by an imbalance between energy production and demand. Magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) provide the unique opportunity for in vivo assessment of several fundamental events in tissue metabolism without the use of ionizing radiation. Of particular interest, phosphate metabolites that are involved in ATP generation and utilization can be quantified noninvasively by phosphorous-31 (31P) MRS/MRI. Furthermore, 31P magnetization transfer (MT) techniques allow in vivo measurement of metabolic fluxes via creatine kinase (CK) and ATP synthase. However, a major impediment for the clinical applications of 31P-MRS/MRI is the prohibitively long acquisition time and/or the low spatial resolution that are necessary to achieve adequate signal-to-noise ratio. In this review, current 31P-MRS/MRI techniques used in basic science and clinical research are presented. Recent advances in the development of fast 31P-MRS/MRI methods are also discussed.
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Affiliation(s)
- Yuchi Liu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Yuning Gu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Xin Yu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Radiology, Case Western Reserve University, Cleveland, OH, USA
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
- Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, USA
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11
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Valkovič L, Chmelík M, Krššák M. In-vivo 31P-MRS of skeletal muscle and liver: A way for non-invasive assessment of their metabolism. Anal Biochem 2017; 529:193-215. [PMID: 28119063 PMCID: PMC5478074 DOI: 10.1016/j.ab.2017.01.018] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 01/13/2017] [Accepted: 01/19/2017] [Indexed: 01/18/2023]
Abstract
In addition to direct assessment of high energy phosphorus containing metabolite content within tissues, phosphorus magnetic resonance spectroscopy (31P-MRS) provides options to measure phospholipid metabolites and cellular pH, as well as the kinetics of chemical reactions of energy metabolism in vivo. Even though the great potential of 31P-MR was recognized over 30 years ago, modern MR systems, as well as new, dedicated hardware and measurement techniques provide further opportunities for research of human biochemistry. This paper presents a methodological overview of the 31P-MR techniques that can be used for basic, physiological, or clinical research of human skeletal muscle and liver in vivo. Practical issues of 31P-MRS experiments and examples of potential applications are also provided. As signal localization is essential for liver 31P-MRS and is important for dynamic muscle examinations as well, typical localization strategies for 31P-MR are also described.
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Affiliation(s)
- Ladislav Valkovič
- High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Oxford, United Kingdom; Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia.
| | - Marek Chmelík
- High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria; Institute for Clinical Molecular MRI in Musculoskeletal System, Karl Landsteiner Society, Vienna, Austria
| | - Martin Krššák
- High-field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria; Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
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12
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Ren J, Sherry AD, Malloy CR. Efficient 31 P band inversion transfer approach for measuring creatine kinase activity, ATP synthesis, and molecular dynamics in the human brain at 7 T. Magn Reson Med 2016; 78:1657-1666. [PMID: 27868234 DOI: 10.1002/mrm.26560] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 10/16/2016] [Accepted: 11/03/2016] [Indexed: 01/28/2023]
Abstract
PURPOSE To develop an efficient 31 P magnetic resonance spectroscopy (MRS) method for measuring creatine kinase (CK) activity, adenosine triphosphate (ATP) synthesis, and motion dynamics in the human brain at 7 Tesla (T). METHODS Three band inversion modules differing in center frequency were used to induce magnetization transfer (MT) effect in three exchange pathways: (i) CK-mediated reaction PCr → γ-ATP; (ii) de novo ATP synthesis Pi → γ-ATP; and (iii) ATP intramolecular 31 P-31 P cross-relaxation γ-(α-) ↔ β-ATP. The resultant MT data were analyzed using a 5-pool model in the format of magnetization matrix according to Bloch-McConnell-Solomon formalism. RESULTS With a repetition time (TR) of 4 s, the scan time for each module was approximately 8 min. The rate constants were kPCr → γATP 0.38 ± 0.02 s-1 , kPi → γATP 0.19 ± 0.02 s-1 , and σγ(α) ↔ βATP 0.19 ± 0.04 s-1 , corresponding to ATP rotation correlation time τc (0.8 ± 0.2) ·10-7 s. The T1 relaxation times were Pi 7.26 ± 1.76 s, PCr 5.99 ± 0.58 s, γ-ATP 0.98 ± 0.07 s, α-ATP 0.95 ± 0.04 s, and β-ATP 0.68 ± 0.03 s. CONCLUSION Short-TR band inversion modules provide a time-efficient way of measuring brain ATP metabolism and could be useful in studying metabolic disorders in brain diseases. Magn Reson Med 78:1657-1666, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, 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 Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Chemistry, University of Texas at Dallas, Richardson, Texas, USA
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,VA North Texas Health Care System, Dallas, Texas, USA
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13
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Ren J, Sherry AD, Malloy CR. A simple approach to evaluate the kinetic rate constant for ATP synthesis in resting human skeletal muscle at 7 T. NMR IN BIOMEDICINE 2016; 29:1240-8. [PMID: 25943328 PMCID: PMC4673044 DOI: 10.1002/nbm.3310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 03/25/2015] [Accepted: 03/27/2015] [Indexed: 05/11/2023]
Abstract
Inversion transfer (IT) is a well-established technique with multiple attractive features for analysis of kinetics. However, its application in measurement of ATP synthesis rate in vivo has lagged behind the more common saturation transfer (ST) techniques. One well-recognized issue with IT is the complexity of data analysis in comparison with much simpler analysis by ST. This complexity arises, in part, because the γ-ATP spin is involved in multiple chemical reactions and magnetization exchanges, whereas Pi is involved in a single reaction, Pi → γ-ATP. By considering the reactions involving γ-ATP only as a lumped constant, the rate constant for the reaction of physiological interest, kPi→γATP , can be determined. Here, we present a new IT data analysis method to evaluate kPi→γATP using data collected from resting human skeletal muscle at 7 T. The method is based on the basic Bloch-McConnell equation, which relates kPi→γATP to m˙Pi, the rate of Pi magnetization change. The kPi→γATP value is accessed from m˙Pi data by more familiar linear correlation approaches. For a group of human subjects (n = 15), the kPi→γATP value derived for resting calf muscle was 0.066 ± 0.017 s(-1) , in agreement with literature-reported values. In this study we also explored possible time-saving strategies to speed up data acquisition for kPi→γATP evaluation using simulations. The analysis indicates that it is feasible to carry out a (31) P IT experiment in about 10 min or less at 7 T with reasonable outcome in kPi→γATP variance for measurement of ATP synthesis in resting human skeletal muscle. We believe that this new IT data analysis approach will facilitate the wide acceptance of IT to evaluate ATP synthesis rate in vivo. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - A. Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Chemistry, University of Texas at Dallas, Richardson, TX75080
| | - Craig R. Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX75390
- VA North Texas Health Care System, Dallas, TX75216
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Affourtit C. Mitochondrial involvement in skeletal muscle insulin resistance: A case of imbalanced bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1678-93. [PMID: 27473535 DOI: 10.1016/j.bbabio.2016.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/19/2016] [Accepted: 07/23/2016] [Indexed: 12/16/2022]
Abstract
Skeletal muscle insulin resistance in obesity associates with mitochondrial dysfunction, but the causality of this association is controversial. This review evaluates mitochondrial models of nutrient-induced muscle insulin resistance. It transpires that all models predict that insulin resistance arises as a result of imbalanced cellular bioenergetics. The nature and precise origin of the proposed insulin-numbing molecules differ between models but all species only accumulate when metabolic fuel supply outweighs energy demand. This observation suggests that mitochondrial deficiency in muscle insulin resistance is not merely owing to intrinsic functional defects, but could instead be an adaptation to nutrient-induced changes in energy expenditure. Such adaptive effects are likely because muscle ATP supply is fully driven by energy demand. This market-economic control of myocellular bioenergetics offers a mechanism by which insulin-signalling deficiency can cause apparent mitochondrial dysfunction, as insulin resistance lowers skeletal muscle anabolism and thus dampens ATP demand and, consequently, oxidative ATP synthesis.
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Affiliation(s)
- Charles Affourtit
- School of Biomedical and Healthcare Sciences, Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth University, Drake Circus, PL4 8AA Plymouth, UK.
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15
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Pouymayou B, Buehler T, Kreis R, Boesch C. Test-retest analysis of multiple 31 P magnetization exchange pathways using asymmetric adiabatic inversion. Magn Reson Med 2016; 78:33-39. [PMID: 27455454 DOI: 10.1002/mrm.26337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/31/2016] [Accepted: 06/17/2016] [Indexed: 01/08/2023]
Abstract
PURPOSE A 31 P-MR inversion transfer (IT) method with a short adiabatic inversion pulse is proposed and its test-retest reliability was evaluated for two spectral fitting strategies. METHODS Assessment in a test-retest design (3 Tesla, vastus muscles, 12 healthy volunteers, 14 inversion times, 22 ms asymmetric adiabatic inversion pulse, adiabatic excitation); spectral fitting in Fitting Tool for Interrelated Arrays of Datasets (FitAID) and Java Magnetic Resonance User Interface (jMRUI); least squares solution of the Bloch-McConnell-Solomon matrix formalism including all 14 measured time-points with equal weighting. RESULTS The cohort averages of k[PCr→γ-ATP] (phosphocreatine, PCr; adenosine triphosphate, ATP) are 0.246 ± 0.050s-1 versus 0.254 ± 0.050s-1 , and k[Pi→γ-ATP] 0.086 ± 0.033s-1 versus 0.066 ± 0.034s-1 (average ± standard deviation, jMRUI versus FitAID). Coefficients of variation of the differences between test and retest are lowest (9.5%) for k[PCr→γ-ATP] fitted in FitAID, larger (15.2%) for the fit in jMRUI, and considerably larger for k[Pi→γ-ATP] fitted in FitAID (43.4%) or jMRUI (47.9%). The beginning of the IT effect can be observed with magnetizations above 92% for noninverted lines while inversion of the ATP resonances is better than -72%. CONCLUSION The performance of the asymmetric adiabatic pulse allows an accurate observation of IT effects even in the early phase; the least squares fit of the Bloch-McConnell-Solomon matrix formalism is robust; and the type of spectral fitting can influence the results significantly. Magn Reson Med 78:33-39, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Bertrand Pouymayou
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Tania Buehler
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Roland Kreis
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
| | - Chris Boesch
- Department of Clinical Research and Department of Radiology, University of Bern, Switzerland
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16
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Ren J, Sherry AD, Malloy CR. Band inversion amplifies 31 P- 31 P nuclear overhauser effects: Relaxation mechanism and dynamic behavior of ATP in the human brain by 31 P MRS at 7 T. Magn Reson Med 2016; 77:1409-1418. [PMID: 27060982 DOI: 10.1002/mrm.26236] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/22/2016] [Accepted: 03/14/2016] [Indexed: 01/07/2023]
Abstract
PURPOSE To develop an improved method to measure the 31 P nuclear Overhauser effect (NOE) for evaluation of adenosine triphosphate (ATP) dynamics in terms of correlation time (τc ), and contribution of dipole-dipole (DD) and chemical shift anisotropy (CSA) mechanisms to T1 relaxation of ATP in human brain. METHODS The NOE of ATP in human brain was evaluated by monitoring changes in magnetization in the β-ATP signal following a band inversion of all downfield 31 P resonances. The magnetization changes observed were analyzed using the Bloch-McConnell-Solomon formulation to evaluate the relaxation and motion dynamic parameters that describe interactions of ATP with cellular solids in human brain tissue. RESULTS The maximal transient NOE, observed as a reduction in the β-ATP signal, was 24 ± 2% upon band inversion of γ- and α-ATP, which is 2-3-fold higher than achievable by frequency-selective inversion of either γ- or α-ATP. The rate of 31 P-31 P cross relaxation (0.21 ± 0.02 s-1 ) led to a τc value of (9.1 ± 0.8) × 10-8 s for ATP in human brain. The T1 relaxation of β-ATP is dominated by CSA over the DD mechanism (60%: 40%). CONCLUSIONS The band inversion method proved effective in amplifying 31 P NOE, and thus facilitating ATP τc and relaxation measurements. This technique renders ATP a potentially useful reporter molecule for cellular environments. Magn Reson Med 77:1409-1418, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390
| | - A Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390.,Department of Chemistry, University of Texas at Dallas, Richardson, TX, 75080
| | - Craig R Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390.,Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390.,VA North Texas Health Care System, Dallas, TX, 75216
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17
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Sleigh A, Savage DB, Williams GB, Porter D, Carpenter TA, Brindle KM, Kemp GJ. 31P magnetization transfer measurements of Pi→ATP flux in exercising human muscle. J Appl Physiol (1985) 2016; 120:649-56. [PMID: 26744504 PMCID: PMC4796179 DOI: 10.1152/japplphysiol.00871.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/02/2016] [Indexed: 11/22/2022] Open
Abstract
Fundamental criticisms have been made over the use of (31)P magnetic resonance spectroscopy (MRS) magnetization transfer estimates of inorganic phosphate (Pi)→ATP flux (VPi-ATP) in human resting skeletal muscle for assessing mitochondrial function. Although the discrepancy in the magnitude of VPi-ATP is now acknowledged, little is known about its metabolic determinants. Here we use a novel protocol to measure VPi-ATP in human exercising muscle for the first time. Steady-state VPi-ATP was measured at rest and over a range of exercise intensities and compared with suprabasal oxidative ATP synthesis rates estimated from the initial rates of postexercise phosphocreatine resynthesis (VATP). We define a surplus Pi→ATP flux as the difference between VPi-ATP and VATP. The coupled reactions catalyzed by the glycolytic enzymes GAPDH and phosphoglycerate kinase (PGK) have been shown to catalyze measurable exchange between ATP and Pi in some systems and have been suggested to be responsible for this surplus flux. Surplus VPi-ATP did not change between rest and exercise, even though the concentrations of Pi and ADP, which are substrates for GAPDH and PGK, respectively, increased as expected. However, involvement of these enzymes is suggested by correlations between absolute and surplus Pi→ATP flux, both at rest and during exercise, and the intensity of the phosphomonoester peak in the (31)P NMR spectrum. This peak includes contributions from sugar phosphates in the glycolytic pathway, and changes in its intensity may indicate changes in downstream glycolytic intermediates, including 3-phosphoglycerate, which has been shown to influence the exchange between ATP and Pi catalyzed by GAPDH and PGK.
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Affiliation(s)
- Alison Sleigh
- Wolfson Brain Imaging Centre, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, United Kingdom; National Institute for Health Research/Wellcome Trust Clinical Research Facility at Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, United Kingdom;
| | - David B Savage
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-Medical Research Council Institute of Metabolic Science, Cambridge Biomedical Campus, United Kingdom
| | - Guy B Williams
- Wolfson Brain Imaging Centre, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, United Kingdom
| | - David Porter
- Fraunhofer MEVIS, Institute for Medical Image Computing, Bremen, Germany
| | - T Adrian Carpenter
- Wolfson Brain Imaging Centre, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, United Kingdom
| | - Kevin M Brindle
- Department of Biochemistry, University of Cambridge, United Kingdom; Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge Biomedical Campus, United Kingdom
| | - Graham J Kemp
- Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, United Kingdom; and Department of Musculoskeletal Biology and MRC - Arthritis Research UK Centre for Integrated research into Musculoskeletal Ageing, Institute of Ageing and Chronic Disease, University of Liverpool, United Kingdom
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18
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Ren J, Sherry AD, Malloy CR. Amplification of the effects of magnetization exchange by (31) P band inversion for measuring adenosine triphosphate synthesis rates in human skeletal muscle. Magn Reson Med 2015; 74:1505-14. [PMID: 25469992 PMCID: PMC4792267 DOI: 10.1002/mrm.25514] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 09/23/2014] [Accepted: 10/09/2014] [Indexed: 01/06/2023]
Abstract
PURPOSE The goal of this study was to amplify the effects of magnetization exchange between γ-adenosine triphosphate (ATP) and inorganic phosphate (Pi) for evaluation of ATP synthesis rates in human skeletal muscle. METHODS The strategy works by simultaneously inverting the (31) P resonances of phosphocreatine (PCr) and ATP using a wide bandwidth, adiabatic inversion radiofrequency pulse followed by observing dynamic changes in intensity of the noninverted Pi signal versus the delay time between the inversion and observation pulses. This band inversion technique significantly delays recovery of γ-ATP magnetization; consequently, the exchange reaction, Pi ↔ γ-ATP, is readily detected and easily analyzed. RESULTS The ATP synthesis rate measured from high-quality spectral data using this method was 0.073 ± 0.011 s(-1) in resting human skeletal muscle (N = 10). The T1 of Pi was 6.93 ± 1.90 s, consistent with the intrinsic T1 of Pi at this field. The apparent T1 of γ-ATP was 4.07 ± 0.32 s, about two-fold longer than its intrinsic T1 due to storage of magnetization in PCr. CONCLUSION Band inversion provides an effective method to amplify the effects of magnetization transfer between γ-ATP and Pi. The resulting data can be easily analyzed to obtain the ATP synthesis rate using a two-site exchange model.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - A. Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Chemistry, University of Texas at Dallas, Richardson, TX75080
| | - Craig R. Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX75390
- VA North Texas Health Care System, Dallas, TX75216
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Ren J, Sherry AD, Malloy CR. (31)P-MRS of healthy human brain: ATP synthesis, metabolite concentrations, pH, and T1 relaxation times. NMR IN BIOMEDICINE 2015; 28:1455-62. [PMID: 26404723 PMCID: PMC4772768 DOI: 10.1002/nbm.3384] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 05/18/2023]
Abstract
The conventional method for measuring brain ATP synthesis is (31)P saturation transfer (ST), a technique typically dependent on prolonged pre-saturation with γ-ATP. In this study, ATP synthesis rate in resting human brain is evaluated using EBIT (exchange kinetics by band inversion transfer), a technique based on slow recovery of γ-ATP magnetization in the absence of B1 field following co-inversion of PCr and ATP resonances with a short adiabatic pulse. The unidirectional rate constant for the Pi → γ-ATP reaction is 0.21 ± 0.04 s(-1) and the ATP synthesis rate is 9.9 ± 2.1 mmol min(-1) kg(-1) in human brain (n = 12 subjects), consistent with the results by ST. Therefore, EBIT could be a useful alternative to ST in studying brain energy metabolism in normal physiology and under pathological conditions. In addition to ATP synthesis, all detectable (31)P signals are analyzed to determine the brain concentration of phosphorus metabolites, including UDPG at around 10 ppm, a previously reported resonance in liver tissues and now confirmed in human brain. Inversion recovery measurements indicate that UDPG, like its diphosphate analogue NAD, has apparent T1 shorter than that of monophosphates (Pi, PMEs, and PDEs) but longer than that of triphosphate ATP, highlighting the significance of the (31)P-(31)P dipolar mechanism in T1 relaxation of polyphosphates. Another interesting finding is the observation of approximately 40% shorter T1 for intracellular Pi relative to extracellular Pi, attributed to the modulation by the intracellular phosphoryl exchange reaction Pi ↔ γ-ATP. The sufficiently separated intra- and extracellular Pi signals also permit the distinction of pH between intra- and extracellular environments (pH 7.0 versus pH 7.4). In summary, quantitative (31)P MRS in combination with ATP synthesis, pH, and T1 relaxation measurements may offer a promising tool to detect biochemical alterations at early stages of brain dysfunctions and diseases.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - A. Dean Sherry
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Chemistry, University of Texas at Dallas, Richardson, TX 75080
| | - Craig R. Malloy
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
- VA North Texas Health Care System, Dallas, TX 75216
- To whom correspondence should be addressed: Craig R. Malloy, 5323 Harry Hines Blvd, NE4.2, Dallas, Texas 75390-8568, USA, (214) 645-2722,
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20
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Rooney WD, Li X, Sammi MK, Bourdette DN, Neuwelt EA, Springer CS. Mapping human brain capillary water lifetime: high-resolution metabolic neuroimaging. NMR IN BIOMEDICINE 2015; 28:607-23. [PMID: 25914365 PMCID: PMC4920360 DOI: 10.1002/nbm.3294] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/28/2015] [Accepted: 03/02/2015] [Indexed: 05/25/2023]
Abstract
Shutter-speed analysis of dynamic-contrast-agent (CA)-enhanced normal, multiple sclerosis (MS), and glioblastoma (GBM) human brain data gives the mean capillary water molecule lifetime (τ(b)) and blood volume fraction (v(b); capillary density-volume product (ρ(†)V)) in a high-resolution (1)H2O MRI voxel (40 μL) or ROI. The equilibrium water extravasation rate constant, k(po) (τ(b)(-1)), averages 3.2 and 2.9 s(-1) in resting-state normal white matter (NWM) and gray matter (NGM), respectively (n = 6). The results (italicized) lead to three major conclusions. (A) k(po) differences are dominated by capillary water permeability (P(W)(†)), not size, differences. NWM and NGM voxel k(po) and v(b) values are independent. Quantitative analyses of concomitant population-averaged k(po), v(b) variations in normal and normal-appearing MS brain ROIs confirm P(W)(†) dominance. (B) P(W)(†) is dominated (>95%) by a trans(endothelial)cellular pathway, not the P(CA)(†) paracellular route. In MS lesions and GBM tumors, P(CA)(†) increases but P(W)(†) decreases. (C) k(po) tracks steady-state ATP production/consumption flux per capillary. In normal, MS, and GBM brain, regional k(po) correlates with literature MRSI ATP (positively) and Na(+) (negatively) tissue concentrations. This suggests that the P(W)(†) pathway is metabolically active. Excellent agreement of the relative NGM/NWM k(po)v(b) product ratio with the literature (31)PMRSI-MT CMR(oxphos) ratio confirms the flux property. We have previously shown that the cellular water molecule efflux rate constant (k(io)) is proportional to plasma membrane P-type ATPase turnover, likely due to active trans-membrane water cycling. With synaptic proximities and synergistic metabolic cooperativities, polar brain endothelial, neuroglial, and neuronal cells form "gliovascular units." We hypothesize that a chain of water cycling processes transmits brain metabolic activity to k(po), letting it report neurogliovascular unit Na(+),K(+)-ATPase activity. Cerebral k(po) maps represent metabolic (functional) neuroimages. The NGM 2.9 s(-1) k(po) means an equilibrium unidirectional water efflux of ~10(15) H2O molecules s(-1) per capillary (in 1 μL tissue): consistent with the known ATP consumption rate and water co-transporting membrane symporter stoichiometries.
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Affiliation(s)
- William D. Rooney
- Advanced Imaging Research CenterOregon Health and Science UniversityPortlandORUSA
- W. M. Keck Foundation High‐Field MRI LaboratoryOregon Health and Science UniversityPortlandORUSA
- Knight Cardiovascular InstituteOregon Health and Science UniversityPortlandORUSA
- Department of NeurologyOregon Health and Science UniversityPortlandORUSA
| | - Xin Li
- Advanced Imaging Research CenterOregon Health and Science UniversityPortlandORUSA
- W. M. Keck Foundation High‐Field MRI LaboratoryOregon Health and Science UniversityPortlandORUSA
| | - Manoj K. Sammi
- Advanced Imaging Research CenterOregon Health and Science UniversityPortlandORUSA
- W. M. Keck Foundation High‐Field MRI LaboratoryOregon Health and Science UniversityPortlandORUSA
| | | | - Edward A. Neuwelt
- Blood‐Brain Barrier ProgramOregon Health and Science UniversityPortlandORUSA
| | - Charles S. Springer
- Advanced Imaging Research CenterOregon Health and Science UniversityPortlandORUSA
- W. M. Keck Foundation High‐Field MRI LaboratoryOregon Health and Science UniversityPortlandORUSA
- Knight Cardiovascular InstituteOregon Health and Science UniversityPortlandORUSA
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21
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Buehler T, Kreis R, Boesch C. Comparison of (31)P saturation and inversion magnetization transfer in human liver and skeletal muscle using a clinical MR system and surface coils. NMR IN BIOMEDICINE 2015; 28:188-199. [PMID: 25483778 DOI: 10.1002/nbm.3242] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 06/04/2023]
Abstract
(31)P MRS magnetization transfer ((31)P-MT) experiments allow the estimation of exchange rates of biochemical reactions, such as the creatine kinase equilibrium and adenosine triphosphate (ATP) synthesis. Although various (31)P-MT methods have been successfully used on isolated organs or animals, their application on humans in clinical scanners poses specific challenges. This study compared two major (31)P-MT methods on a clinical MR system using heteronuclear surface coils. Although saturation transfer (ST) is the most commonly used (31)P-MT method, sequences such as inversion transfer (IT) with short pulses might be better suited for the specific hardware and software limitations of a clinical scanner. In addition, small NMR-undetectable metabolite pools can transfer MT to NMR-visible pools during long saturation pulses, which is prevented with short pulses. (31)P-MT sequences were adapted for limited pulse length, for heteronuclear transmit-receive surface coils with inhomogeneous B1 , for the need for volume selection and for the inherently low signal-to-noise ratio (SNR) on a clinical 3-T MR system. The ST and IT sequences were applied to skeletal muscle and liver in 10 healthy volunteers. Monte-Carlo simulations were used to evaluate the behavior of the IT measurements with increasing imperfections. In skeletal muscle of the thigh, ATP synthesis resulted in forward reaction constants (k) of 0.074 ± 0.022 s(-1) (ST) and 0.137 ± 0.042 s(-1) (IT), whereas the creatine kinase reaction yielded 0.459 ± 0.089 s(-1) (IT). In the liver, ATP synthesis resulted in k = 0.267 ± 0.106 s(-1) (ST), whereas the IT experiment yielded no consistent results. ST results were close to literature values; however, the IT results were either much larger than the corresponding ST values and/or were widely scattered. To summarize, ST and IT experiments can both be implemented on a clinical body scanner with heteronuclear transmit-receive surface coils; however, ST results are much more robust against experimental imperfections than the current implementation of IT.
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Affiliation(s)
- Tania Buehler
- Departments of Clinical Research and Radiology, University of Bern, Switzerland
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22
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Guzun R, Kaambre T, Bagur R, Grichine A, Usson Y, Varikmaa M, Anmann T, Tepp K, Timohhina N, Shevchuk I, Chekulayev V, Boucher F, Dos Santos P, Schlattner U, Wallimann T, Kuznetsov AV, Dzeja P, Aliev M, Saks V. Modular organization of cardiac energy metabolism: energy conversion, transfer and feedback regulation. Acta Physiol (Oxf) 2015; 213:84-106. [PMID: 24666671 DOI: 10.1111/apha.12287] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 12/23/2013] [Accepted: 03/16/2014] [Indexed: 12/19/2022]
Abstract
To meet high cellular demands, the energy metabolism of cardiac muscles is organized by precise and coordinated functioning of intracellular energetic units (ICEUs). ICEUs represent structural and functional modules integrating multiple fluxes at sites of ATP generation in mitochondria and ATP utilization by myofibrillar, sarcoplasmic reticulum and sarcolemma ion-pump ATPases. The role of ICEUs is to enhance the efficiency of vectorial intracellular energy transfer and fine tuning of oxidative ATP synthesis maintaining stable metabolite levels to adjust to intracellular energy needs through the dynamic system of compartmentalized phosphoryl transfer networks. One of the key elements in regulation of energy flux distribution and feedback communication is the selective permeability of mitochondrial outer membrane (MOM) which represents a bottleneck in adenine nucleotide and other energy metabolite transfer and microcompartmentalization. Based on the experimental and theoretical (mathematical modelling) arguments, we describe regulation of mitochondrial ATP synthesis within ICEUs allowing heart workload to be linearly correlated with oxygen consumption ensuring conditions of metabolic stability, signal communication and synchronization. Particular attention was paid to the structure-function relationship in the development of ICEU, and the role of mitochondria interaction with cytoskeletal proteins, like tubulin, in the regulation of MOM permeability in response to energy metabolic signals providing regulation of mitochondrial respiration. Emphasis was given to the importance of creatine metabolism for the cardiac energy homoeostasis.
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Affiliation(s)
- R. Guzun
- Laboratory of Fundamental and Applied Bioenergetics; INSERM U1055; Joseph Fourier University; Grenoble France
- Department of Rehabilitation and Physiology; University Hospital; Grenoble France
| | - T. Kaambre
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - R. Bagur
- Laboratory of Fundamental and Applied Bioenergetics; INSERM U1055; Joseph Fourier University; Grenoble France
- Experimental, Theoretical and Applied Cardio-Respiratory Physiology; Laboratory TIMC-IMAG; UMR5525; Joseph Fourier University; Grenoble France
| | - A. Grichine
- Life Science Imaging - In Vitro Platform; IAB CRI INSERM U823; Joseph Fourier University; Grenoble France
| | - Y. Usson
- Experimental, Theoretical and Applied Cardio-Respiratory Physiology; Laboratory TIMC-IMAG; UMR5525; Joseph Fourier University; Grenoble France
| | - M. Varikmaa
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - T. Anmann
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - K. Tepp
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - N. Timohhina
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - I. Shevchuk
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - V. Chekulayev
- Laboratory of Bioenergetics; National Institute of Chemical Physics and Biophysics; Tallinn Estonia
| | - F. Boucher
- Experimental, Theoretical and Applied Cardio-Respiratory Physiology; Laboratory TIMC-IMAG; UMR5525; Joseph Fourier University; Grenoble France
| | - P. Dos Santos
- University of Bordeaux Segalen; INSERM U1045; Bordeaux France
| | - U. Schlattner
- Laboratory of Fundamental and Applied Bioenergetics; INSERM U1055; Joseph Fourier University; Grenoble France
| | - T. Wallimann
- Emeritus; Biology Department; ETH; Zurich Switzerland
| | - A. V. Kuznetsov
- Cardiac Surgery Research Laboratory; Department of Heart Surgery; Innsbruck Medical University; Innsbruck Austria
| | - P. Dzeja
- Division of Cardiovascular Diseases; Department of Medicine; Mayo Clinic; Rochester MN USA
| | - M. Aliev
- Institute of Experimental Cardiology; Cardiology Research Center; Moscow Russia
| | - V. Saks
- Laboratory of Fundamental and Applied Bioenergetics; INSERM U1055; Joseph Fourier University; Grenoble France
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23
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Parasoglou P, Xia D, Regatte RR. Feasibility of mapping unidirectional Pi-to-ATP fluxes in muscles of the lower leg at 7.0 Tesla. Magn Reson Med 2014; 74:225-230. [PMID: 25078605 DOI: 10.1002/mrm.25388] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/10/2014] [Accepted: 07/05/2014] [Indexed: 12/16/2022]
Abstract
PURPOSE To assess the feasibility of mapping the kinetics and unidirectional fluxes of inorganic phosphate (Pi) to adenosine triphosphate (ATP) reactions in the entire volume of the lower leg muscles using a three-dimensional saturation transfer (ST) phosphorus (31 P) imaging sequence. THEORY AND METHODS We imaged the lower leg muscles of five healthy subjects at 7.0 Tesla. The total experimental time was 45 min. We quantified muscle-specific forward reaction rate constants (k'f ) and metabolic fluxes (Vf ) of the Pi-to-ATP reaction in the tibialis anterior, the gastrocnemius, and the soleus. RESULTS In the tibialis anterior, k'f and Vf were 0.11 s-1 ± 0.03 (mean ± standard deviation) and 0.34 mM s-1 ± 0.10, respectively. In the gastrocnemius, k'f was 0.11 s-1 ± 0.04 and Vf was 0.37 mM s-1 ± 0.11, while in the soleus muscle k'f was 0.10 s-1 ± 0.02 and Vf was 0.36 mM s-1 ± 0.14. CONCLUSION Our results suggest that mapping the kinetics and unidirectional fluxes from Pi-to-ATP in both the anterior and posterior muscles of the lower leg is feasible at ultra-high field and may provide useful insights for the study of insulin resistance, diabetes and aging. Magn Reson Med 74:225-230, 2015. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Prodromos Parasoglou
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Department of Radiology, Center for Biomedical Imaging, New York University Langone Medical Center, New York, New York, USA
| | - Ding Xia
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Department of Radiology, Center for Biomedical Imaging, New York University Langone Medical Center, New York, New York, USA
| | - Ravinder R Regatte
- Quantitative Multinuclear Musculoskeletal Imaging Group (QMMIG), Department of Radiology, Center for Biomedical Imaging, New York University Langone Medical Center, New York, New York, USA
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24
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Ren J, Yang B, Sherry AD, Malloy CR. Exchange kinetics by inversion transfer: integrated analysis of the phosphorus metabolite kinetic exchanges in resting human skeletal muscle at 7 T. Magn Reson Med 2014; 73:1359-69. [PMID: 24733433 DOI: 10.1002/mrm.25256] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 03/06/2014] [Accepted: 03/26/2014] [Indexed: 01/06/2023]
Abstract
PURPOSE To develop an inversion pulse-based, chemical exchange saturation transfer-like method for detection of (31) P magnetization exchanges among all nuclear magnetic resonance visible metabolites suitable for providing an integrated kinetic analysis of phosphorus exchange reactions in vivo. METHODS The exchange kinetics by inversion transfer (EKIT) sequence includes application of a frequency-selective inversion pulse arrayed over the range of relevant (31) P frequencies, followed by a constant delay and a hard readout pulse. A series of EKIT spectra, each given by a plot of Z-magnetization for each metabolite of interest versus frequency of the inversion pulse, can be generated from this single data set. RESULTS EKIT spectra reflect chemical exchange due to known biochemical reactions, cross-relaxation effects, and relayed magnetization transfers due to both processes. The rate constants derived from EKIT data collected on resting human skeletal muscle were: ATP synthesis via ATP synthase (0.050 ± 0.016 s(-1) ), ATP synthesis via creatine kinase (0.264 ± 0.023 s(-1) ), and cross-relaxation between neighboring spin pairs within ATP (0.164 ± 0.022 s(-1) ). CONCLUSION EKIT provides a simple, alternative method to detect chemical exchange, cross relaxation, and relayed magnetization transfer effects in human skeletal muscle at 7 T.
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Affiliation(s)
- Jimin Ren
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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25
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Prompers JJ, Wessels B, Kemp GJ, Nicolay K. MITOCHONDRIA: investigation of in vivo muscle mitochondrial function by 31P magnetic resonance spectroscopy. Int J Biochem Cell Biol 2014; 50:67-72. [PMID: 24569118 DOI: 10.1016/j.biocel.2014.02.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 02/06/2014] [Accepted: 02/16/2014] [Indexed: 01/06/2023]
Abstract
The most important function of mitochondria is the production of energy in the form of ATP. The socio-economic impact of human diseases that affect skeletal muscle mitochondrial function is growing, and improving their clinical management critically depends on the development of non-invasive assays to assess mitochondrial function and monitor the effects of interventions. 31P magnetic resonance spectroscopy provides two approaches that have been used to assess in vivo ATP synthesis in skeletal muscle: measuring Pi→ATP exchange flux using saturation transfer in resting muscle, and measuring phosphocreatine recovery kinetics after exercise. However, Pi→ATP exchange does not represent net mitochondrial ATP synthesis flux and has no simple relationship with mitochondrial function. Post-exercise phosphocreatine recovery kinetics, on the other hand, yield reliable measures of muscle mitochondrial capacity in vivo, whose ability to define the site of functional defects is enhanced by combination with other non-invasive techniques.
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Affiliation(s)
- Jeanine J Prompers
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - Bart Wessels
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Graham J Kemp
- Department of Musculoskeletal Biology and Magnetic Resonance & Image Analysis Research Centre, University of Liverpool, UK
| | - Klaas Nicolay
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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26
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Akki A, Yang H, Gupta A, Chacko VP, Yano T, Leppo MK, Steenbergen C, Walston J, Weiss RG. Skeletal muscle ATP kinetics are impaired in frail mice. AGE (DORDRECHT, NETHERLANDS) 2014; 36:21-30. [PMID: 23695949 PMCID: PMC3889887 DOI: 10.1007/s11357-013-9540-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 05/03/2013] [Indexed: 05/15/2023]
Abstract
The interleukin-10 knockout mouse (IL10(tm/tm)) has been proposed as a model for human frailty, a geriatric syndrome characterized by skeletal muscle (SM) weakness, because it develops an age-related decline in SM strength compared to control (C57BL/6J) mice. Compromised energy metabolism and energy deprivation appear to play a central role in muscle weakness in metabolic myopathies and muscular dystrophies. Nonetheless, it is not known whether SM energy metabolism is altered in frailty. A combination of in vivo (31)P nuclear magnetic resonance experiments and biochemical assays was used to measure high-energy phosphate concentrations, the rate of ATP synthesis via creatine kinase (CK), the primary energy reserve reaction in SM, as well as the unidirectional rates of ATP synthesis from inorganic phosphate (Pi) in hind limb SM of 92-week-old control (n = 7) and IL10(tm/tm) (n = 6) mice. SM Phosphocreatine (20.2 ± 2.3 vs. 16.8 ± 2.3 μmol/g, control vs. IL10(tm/tm), p < 0.05), ATP flux via CK (5.0 ± 0.9 vs. 3.1 ± 1.1 μmol/g/s, p < 0.01), ATP synthesis from inorganic phosphate (Pi → ATP) (0.58 ± 0.3 vs. 0.26 ± 0.2 μmol/g/s, p < 0.05) and the free energy released from ATP hydrolysis (∆G ∼ATP) were significantly lower and [Pi] (2.8 ± 1.0 vs. 5.3 ± 2.0 μmol/g, control vs. IL10(tm/tm), p < 0.05) markedly higher in IL10(tm/tm) than in control mice. These observations demonstrate that, despite normal in vitro metabolic enzyme activities, in vivo SM ATP kinetics, high-energy phosphate levels and energy release from ATP hydrolysis are reduced and inorganic phosphate is elevated in a murine model of frailty. These observations do not prove, but are consistent with the premise, that energetic abnormalities may contribute metabolically to SM weakness in this geriatric syndrome.
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Affiliation(s)
- Ashwin Akki
- />Cardiology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
- />Division of Magnetic Resonance Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Huanle Yang
- />Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Ashish Gupta
- />Cardiology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
- />Division of Magnetic Resonance Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Vadappuram P. Chacko
- />Division of Magnetic Resonance Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Toshiyuki Yano
- />Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Michelle K. Leppo
- />Cardiology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Charles Steenbergen
- />Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Jeremy Walston
- />Division of Geriatric Medicine and Gerontology, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Robert G. Weiss
- />Cardiology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
- />Division of Magnetic Resonance Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD USA
- />The Johns Hopkins Hospital, Blalock 544, 600 N. Wolfe Street, Baltimore, MD 21287-6568 USA
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27
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Schryer DW, Peterson P, Illaste A, Vendelin M. Sensitivity analysis of flux determination in heart by H₂ ¹⁸O -provided labeling using a dynamic Isotopologue model of energy transfer pathways. PLoS Comput Biol 2012; 8:e1002795. [PMID: 23236266 PMCID: PMC3516558 DOI: 10.1371/journal.pcbi.1002795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 08/09/2012] [Indexed: 11/21/2022] Open
Abstract
To characterize intracellular energy transfer in the heart, two organ-level methods have frequently been employed: inversion and saturation transfer, and dynamic labeling. Creatine kinase (CK) fluxes obtained by following oxygen labeling have been considerably smaller than the fluxes determined by saturation transfer. It has been proposed that dynamic labeling determines net flux through CK shuttle, whereas saturation transfer measures total unidirectional flux. However, to our knowledge, no sensitivity analysis of flux determination by oxygen labeling has been performed, limiting our ability to compare flux distributions predicted by different methods. Here we analyze oxygen labeling in a physiological heart phosphotransfer network with active CK and adenylate kinase (AdK) shuttles and establish which fluxes determine the labeling state. A mathematical model consisting of a system of ordinary differential equations was composed describing enrichment in each phosphoryl group and inorganic phosphate. By varying flux distributions in the model and calculating the labeling, we analyzed labeling sensitivity to different fluxes in the heart. We observed that the labeling state is predominantly sensitive to total unidirectional CK and AdK fluxes and not to net fluxes. We conclude that measuring dynamic incorporation of into the high-energy phosphotransfer network in heart does not permit unambiguous determination of energetic fluxes with a higher magnitude than the ATP synthase rate when the bidirectionality of fluxes is taken into account. Our analysis suggests that the flux distributions obtained using dynamic labeling, after removing the net flux assumption, are comparable with those from inversion and saturation transfer. In heart, the movement of energy metabolites between force-producing myosin, other ATPases, and mitochondria is vital for its function and closely related to heart pathologies. In addition to diffusion, transport of ATP, ADP, Pi, and phosphocreatine occurs along parallel pathways such as the adenylate kinase and creatine kinase shuttles. Two organ-level methods have been developed to study the relative flux through these pathways. However, their results differ. It was recently demonstrated that studies often suffer from the exclusion of compartmentation from their metabolic models. One study overcame this limitation by using compartmental models and statistical methods on multiple experiments. Here, we analyzed the sensitivity of the other method - dynamic labeling of phosphoryl groups and inorganic phosphate. For that, we composed a mathematical model tracking enrichment of the metabolites and evaluated sensitivity of labeling to different flux distribution scenarios. Our study shows that the dynamic method provides a measure of total flux, and not net flux as presumed previously, making the fluxes predicted from both methods consistent. Importantly, conclusions derived on the basis of labeling analysis, particularly those regarding the net flux through the shuttles in control and pathological cases, need to be reevaluated.
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Affiliation(s)
| | | | | | - Marko Vendelin
- Laboratory of Systems Biology, Institute of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
- * E-mail:
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28
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Befroy DE, Rothman DL, Petersen KF, Shulman GI. ³¹P-magnetization transfer magnetic resonance spectroscopy measurements of in vivo metabolism. Diabetes 2012; 61:2669-78. [PMID: 23093656 PMCID: PMC3478545 DOI: 10.2337/db12-0558] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Magnetic resonance spectroscopy offers a broad range of noninvasive analytical methods for investigating metabolism in vivo. Of these, the magnetization-transfer (MT) techniques permit the estimation of the unidirectional fluxes associated with metabolic exchange reactions. Phosphorus (³¹P) MT measurements can be used to examine the bioenergetic reactions of the creatine-kinase system and the ATP synthesis/hydrolysis cycle. Observations from our group and others suggest that the inorganic phosphate (P(i)) → ATP flux in skeletal muscle may be modulated by certain conditions, including aging, insulin resistance, and diabetes, and may reflect inherent alterations in mitochondrial metabolism. However, such effects on the P(i) → ATP flux are not universally observed under conditions in which mitochondrial function, assessed by other techniques, is impaired, and recent articles have raised concerns about the absolute magnitude of the measured reaction rates. As the application of ³¹P-MT techniques becomes more widespread, this article reviews the methodology and outlines our experience with its implementation in a variety of models in vivo. Also discussed are potential limitations of the technique, complementary methods for assessing oxidative metabolism, and whether the P(i) → ATP flux is a viable biomarker of metabolic function in vivo.
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Affiliation(s)
- Douglas E Befroy
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT, USA.
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29
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Abstract
Magnetic resonance spectroscopy (MRS) methods offer a potentially valuable window into cellular metabolism. Measurement of flux between inorganic phosphate (Pi) and ATP using (31)P MRS magnetization transfer has been used in resting muscle to assess what is claimed to be mitochondrial ATP synthesis and has been particularly popular in the study of insulin effects and insulin resistance. However, the measured Pi→ATP flux in resting skeletal muscle is far higher than the true rate of oxidative ATP synthesis, being dominated by a glycolytically mediated Pi↔ATP exchange reaction that is unrelated to mitochondrial function. Furthermore, even if measured accurately, the ATP production rate in resting muscle has no simple relationship to mitochondrial capacity as measured either ex vivo or in vivo. We summarize the published measurements of Pi→ATP flux, concentrating on work relevant to diabetes and insulin, relate it to current understanding of the physiology of mitochondrial ATP synthesis and glycolytic Pi↔ATP exchange, and discuss some possible implications of recently reported correlations between Pi→ATP flux and other physiological measures.
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Affiliation(s)
- Graham J Kemp
- Department of Musculoskeletal Biology and Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, Liverpool, UK.
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30
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Nabuurs CI, Hilbers CW, Wieringa B, Heerschap A. Letter to the editor: “Interpretation of 31P NMR saturation transfer experiments: do not forget the spin relaxation properties”. Am J Physiol Cell Physiol 2012; 302:C1566-7. [DOI: 10.1152/ajpcell.00409.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- C. I. Nabuurs
- Department of Radiology, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands
| | - C. W. Hilbers
- Laboratory of Physical Chemistry, Faculty of Science, Radboud University, Nijmegen, Netherlands; and
| | - B. Wieringa
- Department of Cell Biology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands
| | - A. Heerschap
- Department of Radiology, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands
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31
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32
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Nemutlu E, Zhang S, Gupta A, Juranic NO, Macura SI, Terzic A, Jahangir A, Dzeja P. Dynamic phosphometabolomic profiling of human tissues and transgenic models by 18O-assisted ³¹P NMR and mass spectrometry. Physiol Genomics 2012; 44:386-402. [PMID: 22234996 DOI: 10.1152/physiolgenomics.00152.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Next-generation screening of disease-related metabolomic phenotypes requires monitoring of both metabolite levels and turnover rates. Stable isotope (18)O-assisted (31)P nuclear magnetic resonance (NMR) and mass spectrometry uniquely allows simultaneous measurement of phosphometabolite levels and turnover rates in tissue and blood samples. The (18)O labeling procedure is based on the incorporation of one (18)O into P(i) from [(18)O]H(2)O with each act of ATP hydrolysis and the distribution of (18)O-labeled phosphoryls among phosphate-carrying molecules. This enables simultaneous recording of ATP synthesis and utilization, phosphotransfer fluxes through adenylate kinase, creatine kinase, and glycolytic pathways, as well as mitochondrial substrate shuttle, urea and Krebs cycle activity, glycogen turnover, and intracellular energetic communication. Application of expanded (18)O-labeling procedures has revealed significant differences in the dynamics of G-6-P[(18)O] (glycolysis), G-3-P[(18)O] (substrate shuttle), and G-1-P[(18)O] (glycogenolysis) between human and rat atrial myocardium. In human atria, the turnover of G-3-P[(18)O], which defects are associated with the sudden death syndrome, was significantly higher indicating a greater importance of substrate shuttling to mitochondria. Phosphometabolomic profiling of transgenic hearts deficient in adenylate kinase (AK1-/-), which altered levels and mutations are associated to human diseases, revealed a stress-induced shift in metabolomic profile with increased CrP[(18)O] and decreased G-1-P[(18)O] metabolic dynamics. The metabolomic profile of creatine kinase M-CK/ScCKmit-/--deficient hearts is characterized by a higher G-6-[(18)O]P turnover rate, G-6-P levels, glycolytic capacity, γ/β-phosphoryl of GTP[(18)O] turnover, as well as β-[(18)O]ATP and β-[(18)O]ADP turnover, indicating altered glycolytic, guanine nucleotide, and adenylate kinase metabolic flux. Thus, (18)O-assisted gas chromatography-mass spectrometry and (31)P NMR provide a suitable platform for dynamic phosphometabolomic profiling of the cellular energetic system enabling prediction and diagnosis of metabolic diseases states.
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Affiliation(s)
- Emirhan Nemutlu
- Division of Cardiovascular Diseases, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
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33
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Koretsky AP. Early development of arterial spin labeling to measure regional brain blood flow by MRI. Neuroimage 2012; 62:602-7. [PMID: 22245338 DOI: 10.1016/j.neuroimage.2012.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/16/2011] [Accepted: 01/01/2012] [Indexed: 12/31/2022] Open
Abstract
Two major avenues of work converged in the late 1980's and early 1990's to give rise to brain perfusion MRI. The development of anatomical brain MRI quickly had as a major goal the generation of angiograms using tricks to label flowing blood in macroscopic vessels. These ideas were aimed at getting information about microcirculatory flow as well. Over the same time course the development of in vivo magnetic resonance spectroscopy had as its primary goal the assessment of tissue function and in particular, tissue energetics. For this the measurement of the delivery of water to tissue was critical for assessing tissue oxygenation and viability. The measurement of the washin/washout of "freely" diffusible tracers by spectroscopic based techniques pointed the way for quantitative approaches to measure regional blood flow by MRI. These two avenues came together in the development of arterial spin labeling (ASL) MRI techniques to measure regional cerebral blood flow. The early use of ASL to measure brain activation to help verify BOLD fMRI led to a rapid development of ASL based perfusion MRI. Today development and applications of regional brain blood flow measurements with ASL continues to be a major area of activity.
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Affiliation(s)
- Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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34
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From AHL, Ugurbil K. Standard magnetic resonance-based measurements of the Pi→ATP rate do not index the rate of oxidative phosphorylation in cardiac and skeletal muscles. Am J Physiol Cell Physiol 2011; 301:C1-11. [PMID: 21368294 DOI: 10.1152/ajpcell.00345.2010] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Magnetic resonance spectroscopy-based magnetization transfer techniques (MT) are commonly used to assess the rate of oxidative (i.e., mitochondrial) ATP synthesis in intact tissues. Physiologically appropriate interpretation of MT rate data depends on accurate appraisal of the biochemical events that contribute to a specific MT rate measurement. The relative contributions of the specific enzymatic reactions that can contribute to a MT P(i)→ATP rate measurement are tissue dependent; nonrecognition of this fact can bias the interpretation of MT P(i)→ATP rate data. The complexities of MT-based measurements of mitochondrial ATP synthesis rates made in striated muscle and other tissues are reviewed, following which, the adverse impacts of erroneous P(i)→ATP rate data analyses on the physiological inferences presented in selected published studies of cardiac and skeletal muscle are considered.
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Affiliation(s)
- Arthur H L From
- Center for Magnetic Resonance Research, University of Minnesota, 2021 6th Street SE, Minneapolis, MN 55455, USA.
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