Figure 2.

The use of ¹³C glutamine isotope tracer to analyze glutamine metabolism under acidosis. (A) Schematic graph indicating various measured metabolites (and corresponding panels) resulting from the uniformly ¹³C labeled glutamine tracer (green). The ¹³C labeled and unlabeled carbons are indicated in red and black, respectively. (B-G) Relative ¹³C enrichment in the glutamate (B,D), CO₂(C), lactate (E), ribonucleic acids (F) and fatty acids (G) under control or acidosis conditions. Glutamate (B,D) is presented as both the 2 (C2 (D)) and 4 (C2 (B)) labeled carbon subpools. Lactate (E) is presented as the uniformly labeled ¹³C3-labeled lactate. Ribonucleic acids (F) are presented as the ¹³C positions 1 to 4 and ¹³C positions 3 to 5 subpools. Fatty acids (G) are presented as 2-carbon ¹³C-labeled palmitate and oleate. Error bars are mean ± SD, significant P values are indicated (*P ≤0.05, **P ≤0.01, ***P ≤0.001).