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. 2013 Apr 1;123(5):1988–1998. doi: 10.1172/JCI65105

Figure 3. Metabolic model and in vivo glutamate enrichment time course together reveal that lactate is predominantly metabolized in neurons.

Figure 3

(A) Schematic representation of uptake and relevant metabolic fluxes for [3-13C]-lactate and glucose in astrocytes and neurons. (B) In vivo POCE difference spectrum showing the increase of 13C labeling in glutamate (Glu) and glutamine (Gln) C3 and C4 during infusion of [3-13C]-lactate. Glu4, glutamate labeled at C4; Gln4, glutamine labeled at C4; Glx3, sum of glutamate and glutamine labeled at C3; Lac3, lactate labeled at C3; Tmax, Michaelis-Menten constant for glucose transport kinetics; Vpc, pyruvate carboxylase flux; VxA and VxN, exchange rate from α-ketoglutarate (α-KG) to glutamate in astrocytes and neurons; VpdhA and VpdhN, pyruvate dehydrogenase flux in astrocytes and neurons; Vgln, glutamine synthesis rate; Veff, glutamine efflux, set to balance Vpc; Ac-CoA, acetyl-coenzyme A complex.