| Quantitative ATP synthesis in human liver measured by localized 31P spectroscopy using the magnetization transfer experiment. | |
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MedLine Citation:
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PMID: 17910026 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The liver plays a central role in intermediate metabolism. Accumulation of liver fat (steatosis) predisposes to various liver diseases. Steatosis and abnormal muscle energy metabolism are found in insulin-resistant and type-2 diabetic states. To examine hepatic energy metabolism, we measured hepatocellular lipid content, using proton MRS, and rates of hepatic ATP synthesis in vivo, using the 31P magnetization transfer experiment. A suitable localization scheme was developed and applied to the measurements of longitudinal relaxation times (T1) in six healthy volunteers and the ATP-synthesis experiment in nine healthy volunteers. Liver 31P spectra were modelled and quantified successfully using a time domain fit and the AMARES (advanced method for accurate, robust and efficient spectral fitting of MRS data with use of prior knowledge) algorithm describing the essential components of the dataset. The measured T1 relaxation times are comparable to values reported previously at lower field strengths. All nine subjects in whom saturation transfer was measured had low hepatocellular lipid content (1.5 +/- 0.2% MR signal; mean +/- SEM). The exchange rate constant (k) obtained was 0.30 +/- 0.02 s(-1), and the rate of ATP synthesis was 29.5 +/- 1.8 mM/min. The measured rate of ATP synthesis is about three times higher than in human skeletal muscle and human visual cortex, but only about half of that measured in perfused rat liver. In conclusion, 31P MRS at 3 T provides sufficient sensitivity to detect magnetization transfer effects and can therefore be used to assess ATP synthesis in human liver. |
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Authors:
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A I Schmid; M Chmelík; J Szendroedi; M Krssák; A Brehm; E Moser; M Roden |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: NMR in biomedicine Volume: 21 ISSN: 0952-3480 ISO Abbreviation: NMR Biomed Publication Date: 2008 Jun |
Date Detail:
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Created Date: 2008-06-03 Completed Date: 2008-09-02 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8915233 Medline TA: NMR Biomed Country: England |
Other Details:
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Languages: eng Pagination: 437-43 Citation Subset: IM |
Copyright Information:
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Copyright (c) 2007 John Wiley & Sons, Ltd. |
Affiliation:
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Karl-Landsteiner Institute of Endocrinology and Metabolism, Hanusch Hospital, Vienna, Austria. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Triphosphate
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analysis*,
biosynthesis Adult Brain / metabolism Energy Metabolism Female Hepatocytes / metabolism Humans Kinetics Lipid Metabolism Liver / metabolism* Magnetic Resonance Spectroscopy / methods* Male Muscle, Skeletal / metabolism Phospholipids / analysis Phosphorus Isotopes / metabolism, pharmacokinetics* Protons Sensitivity and Specificity |
| Chemical | |
Reg. No./Substance:
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0/Phospholipids; 0/Phosphorus Isotopes; 0/Protons; 56-65-5/Adenosine Triphosphate |
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