MATHEMATICAL-MODELING FOR THE GENERATION OF L-[3-H-2,3-C-13]LACTIC ACID ISOTOPOMERS BY ERYTHROCYTES EXPOSED TO EITHER D-[1-C-13]GLUCOSE OR D-[6-C-13]GLUCOSE IN THE PRESENCE OF (H2O)-H-2

The production of C-3-trisdeuterated, bisdeuterated, monodeuterated or non-deuterated L-[3-C-13]lactate by human erythrocytes exposed to either D-[1-C-13]glucose or D-[6-C-13]glucose in the presence of (H2O)-H-2 can be assessed by C-13 NMR spectroscopy. Such a deuteration may occur at the level of the reactions catalyzed by phosphoglucoisomerase, phosphomannoisomerase, pyruvate kinase and glutamate-pyruvate transaminase. In this report, a mathematical model is proposed for the analysis of experimental data. It allows to estimate the relative extent of deuteration at each step of D-glucose metabolism. This approach may thus provide novel information on the extent of back-and-forth interconversion of either hexose 6-phosphates in both the phosphoglucoisomerase and phosphomannoisomerase reactions or pyruvate and L-alanine in the reaction catalyzed by glutamate-pyruvate transaminase.