title: Modeling of brain metabolism and pyruvate compartmentation using (13)C NMR in vivo: caution required.
abstract: Two variants of a widely used two-compartment model were prepared for fitting the time course of [1,6-(13)C2]glucose metabolism in rat brain. Features common to most models were included, but in one model the enrichment of the substrates entering the glia and neuronal citric acid cycles was allowed to differ. Furthermore, the models included the capacity to analyze multiplets arising from (13)C spin-spin coupling, known to improve parameter estimates in heart. Data analyzed were from a literature report providing time courses of [1,6-(13)C2]glucose metabolism. Four analyses were used, two comparing the effect of different pyruvate enrichment in glia and neurons, and two for determining the effect of multiplets present in the data. When fit independently, the enrichment in glial pyruvate was less than in neurons. In the absence of multiplets, fit quality and parameter values were typical of those in the literature, whereas the multiplet curves were not modeled well. This prompted the use of robust statistical analysis (the Kolmogorov-Smirnov test of goodness of fit) to determine whether individual curves were modeled appropriately. At least 50% of the curves in each experiment were considered poorly fit. It was concluded that the model does not include all metabolic features required to analyze the data.
authors: Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. Mark.Jeffrey@UTSouthwestern.edu
authors: F Mark
authors: FM
authors: Jeffrey
authors: Isaac
authors: I
authors: Marin-Valencia
authors: Levi B
authors: LB
authors: Good
authors: Alexander A
authors: AA
authors: Shestov
authors: Pierre-Gilles
authors: PG
authors: Henry
authors: Juan M
authors: JM
authors: Pascual
authors: Craig R
authors: CR
authors: Malloy
mesh_terms: D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D002250:Carbon Radioisotopes; D002952:Citric Acid Cycle / Q000502:physiology; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D015233:Models, Statistical; D009457:Neuroglia / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism*; D051381:Rats
chemical_list: D002250:Carbon Radioisotopes; D005973:Glutamine; D018698:Glutamic Acid; D019289:Pyruvic Acid; D005947:Glucose
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