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. 2013 Dec 3;9:712. doi: 10.1038/msb.2013.65

Figure 1.

Figure 1

Glutamine-driven oxidative phosphorylation supports ATP production in iBMK-parental cells. (A) Redox-balanced metabolic flux analysis scheme. Experimental measurements including uptake/excretion rates and steady-state intracellular labeling patterns were input into a redox-balanced metabolic flux analysis model. Fluxes with confidence intervals were obtained by optimizing the simulation to fit the steady-state experimental observations. The resulting fluxes also fit kinetic labeling data well. (B) Metabolic fluxes in the parental iBMK cell line. Numbers indicate metabolic flux in nmole/h/μl cells. Colors indicate the contribution of glucose (yellow) or glutamine (blue) in driving each redox reaction. Reactions that do not produce high energy electrons are shown in black. Font size reflects absolute metabolite concentrations. Pyr, pyruvate; AKG, α-ketoglutarate; OAA, oxaloacetate. (C) Effect of oxidative phosphorylation inhibitors on the ATP/ADP ratio and NADH/NAD+ ratio. Absolute concentrations of ATP, ADP, NADH, and NAD+ were measured by isotope ratio-based MS 5 min after addition of vehicle (DMSO), the complex III inhibitor antimycin A (4 μg/ml) or the ATP synthase inhibitor oligomycin (8 μg/ml) (mean ± s.d. of N=3). (D) Oxygen consumption rates and NADH/NAD+ ratio measured after switching cells to complete media or media lacking glucose or glutamine for 8 h (mean±s.d. of N=3).