Quantifying endogenous glucose production and contributing source fluxes from a single 2H NMR spectrum

Abstract

Endogenous glucose production (EGP), gluconeogenic and glycogenolytic fluxes by analysis of a single 2H-NMR spectrum is demonstrated with 6-hr and 24-hr fasted rats. Animals were administered [1-2H, 1- 13C]glucose, a novel tracer of glucose turnover, and 2H2O. Plasma glucose enrichment from both tracers was quantified by 2H-NMR analysis of monoacetone glucose. The 6-hr fasted group (n = 7) had EGP rates of 95.6 ± 13.3 μmol/kg/min, where 56.2 ± 7.9 μmol/kg/min were derived from PEP; 12.1 ± 2.1 μmol/kg/min from glycerol, and 32.1 ± 4.9 μmol/kg/min from glycogen. The 24-hr fasted group (n = 7) had significantly lower EGP rates (52.8 ± 7.2 μmol/kg/min, P = 0.004 vs. 6 hr) mediated by a significantly reduced contribution from glycogen (4.7 ± 5.9 μmol/kg/min, P = 0.02 vs. 6 hr) while PEP and glycerol contributions were not significantly different (39.5 ± 3.9 and 8.5 ± 1.2 μmol/kg/min, respectively). These estimates agree with previous assays of EGP fluxes in fasted rats obtained by multinuclear NMR analyses of plasma glucose enrichment from 2H 2O and 13C-glucose tracers. © 2009 Wiley-Liss, Inc.