Figure 2: Adaptation via glycolysis and the pentose cycle of HepG2 cells to glucose or fructose treatment. Glucose (Gluc; 5 mM, middle dark bars) or fructose (Fruct; 5 mM, dark bars) was added to the baseline 4.5mM glucose (Cont; 4.5 mM glucose, white bars). Ten percent (0.5 mM) glucose was supplied in the form of [1,2-13C2]-D-glucose as the single metabolic tracer in each culture and replaced every 24-h for a total of 72 hours culture. A, 13C labeled lactate fraction as percent of total unlabeled lactate in the media; B, Media lactate M+1 SmC1-C3 (one 13C substitution, m/z 328 ion, chemical ionization) of its 13C labeled fraction; C, Media lactate M+2 SmC1-C3 (two 13C substitutions, m/z 328 fragment, chemical ionization) of its 13C labeled fraction; D, Pentose cycle flux relative to glycolysis via glucose-6Pdehydrogenase (G6PDH), transketolase and transaldoase; E Triose futile cycling into M+3 SÁΧ2−Χ3 (two 13C substitutions, m/z 328 fragment, chemical ionization) of its 13C labeled fraction; F, Media lactate concentrations as integrated chromatographic peak area (arbitrary values); (n=3; *p < 0.05).