1-13C]glucose metabolism in brain cells: isotopomer analysis of glutamine from cerebellar astrocytes and glutamate from granule cells

Developmental Neuroscience
M MerleP Canioni

Abstract

We analyzed the glutamine isotopomers released into the extracellular medium by cerebellar astrocytes incubated with [1-13C]glucose. We developed a mathematical model of the tricarboxylic acid (TCA) cycle to determine the relative flux of molecules through the anaplerotic versus oxidative pathways and the relative pyruvate carboxylase versus pyruvate dehydrogenase activities. As glutamine C2 and C3 exhibited unequivalent enrichments, we examined the possibility of: (1) both the entry of the label into the TCA cycle from pyruvate and the conversion of the oxaloacetate into citrate before equilibration with fumarate, and (2) the occurrence of an orientation-conserved transfer of the symmetrical 4-carbon intermediates. The best fit required partial cycling between oxaloacetate and fumarate, whereas the occurrence of any orientation-conserved transfer was rejected. On the other hand, the analysis of glutamate isotopomers from perchloric acid extracts of granule cells incubated with [1-13C]glucose indicated that total cycling of oxaloacetate into fumarate occurred in these cells.

Citations

Dec 18, 2001·Journal of Neuroscience Research·B Hassel
Jul 31, 2007·Glia·Luc PellerinPierre J Magistretti
Mar 22, 2002·The Journal of Pharmacology and Experimental Therapeutics·Ursula SonnewaldMichael Aschner
Mar 4, 2000·Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism·B Hassel, A Bråthe
Nov 6, 2003·Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism·Anne-Karine Bouzier-SoreLuc Pellerin

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