Figure 3

Pathway tracing analysis using ¹³C₆-glucose in ischemic hearts.

(a) Schematic representation of ¹³C₆-glucose utilizing pathway. (b) Cardiac metabolites were fixed by focused microwave irradiation (FMW) 25 min after injecting ¹³C₆-glucose. The inner and outer pies indicate the fractions of ¹³C-labeled metabolites that belong to the specified metabolic pathways and those of each metabolite species. Grey indicates glucose uptake, red amino acid (AA) production (Asp, Gln, Glu), blue tricarboxylic acid (TCA) cycle (citrate, 2-DG, malate) and green glycolysis (G1P, G6P, F6P, F1, 6DP, 3PG, lactate, glycerol 3P). Note that a large fraction of glucose is diverted to the syntheses of glutamate and lactate. Experiments were repeated at least three times with consistent results. Representative pie charts are shown. (c) Experimental protocol for generating the left anterior descending artery (LAD) ligation model. Mice were subjected to LAD ligation or a sham operation at 10 min after injecting ¹³C₆-glucose (1 mg/g body weight in saline, i.p.). After 10 min, myocardial metabolites were snap-fixed in vivo by FMW. (d) Capillary electrophoresis–mass spectrometry (CE-MS) quantification of ¹³C-containing metabolites in the respective blocks are represented as pie charts. Experiments were repeated at least four times with consistent results. Representative pie charts are shown (see Supplementary Fig. S11). (e) Absolute quantification of ¹³C₃ lactate in the respective blocks of LAD-ligated or sham-operated mice (n = 4, for each). Abbreviations: G1P, glucose-1-phosphate; G6P, glucose-6-phosphate; F6P, fructose-6-phosphate; F1,6DP, fructose-1,6-disphosphate; 3PG, 3-phosphoglycerate; Glycerol 3P, glycerol-3-phosphate; α-KG, α-ketoglutarate; Gln, glutamine; Glu, glutamate; Asn, asparagine; Asp, aspartic acid.