Table 2.
The percentage of lactate isotopomers and isotopologues (mean ± SD, n = 12) generated by 4T1, Hela, K562, and thymocytes, traced by [1,2-13C2]glucose (upper part), the percentage of lactate (mean ± SD, n = 12) derived from glycolysis, PPP and other sources (down part).
| [2,3-13C2]lactate | lactate | [2-13C]- or [3-13C]lactate | [1,2-13C2]- or [1,3-13C2]lactate | [1-13C]lactate | [U-13C]lactate | Total generated Lactate | |
|---|---|---|---|---|---|---|---|
| 4T1 | 56% ± 0.43% | 40% ± 0.36% | 1.9% ± 0.099% | 0.74% ± 0.039% | 0.043% ± 0.032% | 1.1% ± 0.041% | 27 ± 2.4 (μmol/million cell/12 h) |
| Hela | 55% ± 1.1% | 41% ± 0.55% | 2.4% ± 0.25% | 0.81% ± 0.13% | 0.11% ± 0.10% | 1.5% ± 0.18% | 40 ± 1.3 (μmol/million cell/12 h) |
| K562 | 56% ± 0.41% | 40% ± 0.46% | 2.1% ± 0.069% | 0.83% ± 0.046% | 0.054% ± 0.032% | 1.1% ± 0.062% | 7.7 ± 0.90 (μmol/million cell/12 h) |
| Thymocytes | 52% ± 0.48% | 44% ± 0.40% | 1.8% ± 0.15% | 0.59% ± 0.037% | 0.19% ± 0.052% | 1.3% ± 0.021% | 60 ± 1.7 (nmol/million cell/12 h) |
| Lactate derived from glycolysis | Lactate derived from nonoxidative PPP | Lactate derived from other sources | |||||
| Glc carbon 1,2,3 | Glc carbon 4,5,6 | Glc carbon 2,3 | Glc carbon 4,5,6 | ||||
| [2,3-13C2]lactate | lactate | [3-13C]lactate | [1,3-13C2]lactate | lactate | lactate | ||
| 4T1 | 56% ± 0.43% | 34% ± 0.41% | 1.9% ± 0.099% | 0.74% ± 0.039% | 4.0% ± 0.18% | 2.2% ± 0.16% | |
| sum | 90% | 6.6% | |||||
| Hela | 55% ± 1.1% | 33% ± 0.26% | 2.4% ± 0.25% | 0.81% ± 0.13% | 4.7% ± 0.57% | 2.3% ± 0.093% | |
| sum | 88% | 7.8% | |||||
| K562 | 56% ± 0.41% | 34% ± 0.64% | 2.1% ± 0.069% | 0.83% ± 0.046% | 4.4% ± 0.17% | 1.5% ± 0.12% | |
| sum | 90% | 7.3% | |||||
| Thymocytes | 52% ± 0.48% | 33% ± 0.48% | 1.8% ± 0.15% | 0.59% ± 0.037% | 3.6% ± 0.25% | 7.9% ± 0.19% | |
| sum | 85% | 6.0% | |||||
4T1, Hela, K562 and thymocyte were incubated in serum-free RPMI-1640 medium containing 6 mM [1,2-13C2]glucose for 12 hours in a humidified CO2 incubator and culture supernatant was collected for LC-MS/MS analysis as described in Materials and Methods. The upper part summarizes the percentage of all lactate isotopologues. The down part assigned the percentage of isotopologues that are generated from glycolysis, pentose phosphate pathway (calculated based on percentage of [3-13C]- and [1,3-13C2]lactate as described in corresponding text), and other sources (according to percentage listed in Table 1). Data are mean ± SD, n = 12, from 2 independent experiments.