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Title: Quantification of the glycogen 13C-1 NMR signal during glycogen synthesis in perfused rat liver
Authors: Bergans, Niki ×
Dresselaers, Tom
Vanhamme, Leentje
Van Hecke, Paul
Van Huffel, Sabine
Vanstapel, Florent #
Issue Date: Feb-2003
Series Title: NMR in biomedicine vol:16 issue:1 pages:36-46
Abstract: We studied glycogen synthesis from glucose in perfused livers of fed (n = 4) and 24 h starved (n = 7) rats. Glycogenolysis was inhibited by BAY R3401 (150 microM) and proglycosyn (100 microM). After 60 min, we replaced 99% (13)C-1 glucose by natural abundance glucose. This pulse-chase design allowed us to recognize residual ongoing futile glycogen turnover from the release of initially deposited (13)C-label, into the (13)C-free chase medium. Net residual turnover was less than 2 +/- 0.7% and 0.6 +/- 0.2% of 1-(13)C glycogen deposition rates of 0.31 +/- 0.04 and 0.99 +/- 0.04 micromol glucose g(-1) min(-1), in starved and fed livers, respectively. The 1-(13)C glycogen signal was monitored throughout the experiment with proton-decoupled (13)C NMR spectroscopy and analyzed in the time domain using AMARES. We noticed progressive line-broadening in any single experiment in the chase phase. One or a sum of two to three overlapping Lorentzians, with different exponential damping factors, were fitted to the signal. When the S/N was better than 40, the fit always delivered a small and a broad component. In the chase phase, the fit with a single Lorentzian resulted in a decline of glycogen signal by about 15 +/- 4 and 12 +/- 2% in starved and fed rats, respectively. This apparent decline in 1-(13)C glycogen signal could not be accounted for by the appearance of equivalent amounts of (13)C-labeled metabolites in the perfusate. The fit with a sum of two Lorentzians resulted in a decline of glycogen signal intensity of 7 +/- 5 and 5 +/- 3% in starved and fed rats, respectively, which reduced the apparent turnover to 8 +/- 9% and 6 +/- 4%, respectively. Quantification of the growing (13)C-1 glycogen signal requires a model function that accommodates changes in line shape throughout the period under study.
URI: 
ISSN: 0952-3480
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biomedical MRI
Electrical Engineering - miscellaneous
Radiology
ESAT - STADIUS, Stadius Centre for Dynamical Systems, Signal Processing and Data Analytics
Laboratory of Clinical Bacteriology and Mycology
Biomedical Quality Assurance Research Unit
× corresponding author
# (joint) last author

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