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. Author manuscript; available in PMC: 2010 Sep 15.
Published in final edited form as: J Neurosci Methods. 2009 Jun 21;182(2):236–243. doi: 10.1016/j.jneumeth.2009.06.015

Fig. 1.

Fig. 1

Schematic diagram of the label incorporation into glutamate, glutamine, aspartate and GABA from [2,5-13C2]glucose. Because both the turnover of glutamate C4 from [1,6-13C2]glucose and that of glutamate C5 from [2-13C2]glucose reflect the same de novo incorporation of exogenous 13C labels into the TCA cycle (Li et al, 2007), only the first turn of the TCA cycle is drawn. 13C labels originated from glucose C2 and C5 carbons are marked with •. Label scrambling during the first turn of the TCA cycle via symmetrical intermediates produces oxaloacetate with labels at C1 or C4. The carbons of glucose, pyruvate, acetyl CoA, α-ketoglutarate, glutamate, glutamine, GABA, oxaloacetate and aspartate are numbered. Abbreviations: AAT: aspartate aminotransferase; Asp: aspartate; GABA-T: GABA transaminase; GAD: glutamic acid decarboxylase; Glc: glucose; Gln: glutamine; Glu: glutamate; GS: glutamine synthetase; α-KG: α-ketoglutarate; OAA: oxaloacetate; PDH: pyruvate dehydrogenase; Pyr: pyruvate.