Figure 5
Pathway tracing analysis using 13C3-lactate in the heart following LAD ligation.
(a) Schematic representation of 13C3-lactate utilizing pathway. (b) Heart metabolites were fixed by focused microwave irradiation (FMW) 1 min after injecting 13C3-lactate. 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. The green area indicates lactate uptake (lactate), red amino acid (AA) production (Asn, Asp, Gln, Glu) and blue tricarboxylic acid (TCA) cycle activity (citrate, malate). Experiments were repeated at least four times with consistent results. Representative pie charts are shown. (c) Experimental protocol for generation of left anterior descending coronary artery (LAD) ligation model. 1 min after injecting 13C3-lactate (1 mg/g body weight in saline, i.v.), mice were subjected to LAD ligation or a sham operation. 10 min later, 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 is represented by pie charts. Experiments were repeated at least four times with consistent results. Representative pie charts are shown. The inner and outer pies indicate the proportion of 13C-labeled metabolites that belong to the specified metabolic pathways and those of each metabolite species. (e) Absolute quantification of 13C3-lactate uptake among the respective blocks of four LAD-ligated or sham-operated mice (n = 4, for each). Abbreviations: Glycerol 3P, glycerol-3-phosphate; Gln, glutamine; Glu, glutamate; Asn, asparagine; Asp, aspartic acid.
