Figure 2.

Altered glucose producing fluxes in glycine N-methyltransferase knockout mice. A, schematic representation of select metabolites and fluxes (highlighted in gray) from ²H/¹³C metabolic flux analysis contributing to endogenous glucose production. B, a time course of fasting arterial blood glucose concentration before and during acquisition of plasma for ²H/¹³C metabolic flux analysis in WT and glycine N-methyltransferase KO mice. C, model-estimated, absolute nutrient fluxes normalized to liver weight (μmol·g liver weight⁻¹·min⁻¹) in mice for endogenous glucose production (V_EndoRa), flux from glycogen to glucose 6-phosphate (V_PYGL), flux from dihydroxyacetone phosphate and glyceraldehyde 3-phosphate (V_Aldo), flux from glycerol to dihydroxyacetone phosphate (V_GK; hexose units), and flux from phosphoenolpyruvate to glyceraldehyde-3-phosphate (V_Enol; hexose units). D, liver glycogen concentration. E, liver PYGL as determined by immunoblotting and representative immunoblot. F, glycogen- and gluconeogenesis-related metabolites: glucose 6-phosphate (G6P), UDP-glucose, fructose 6-phosphate (F6P), dihydroxyacetone phosphate (DHAP), glyceraldehyde 3-phosphate (GAP), glycerol, and phosphoenolpyruvate (PEP). Data are mean ± S.E. (error bars). n = 6–11 mice/group. *, p < 0.05 versus WT.