Delineation of substrate selection and anaplerosis in tricarboxylic acid cycle of the heart by 13C NMR spectroscopy and mass spectrometry.

(13)C NMR and mass spectrometry (MS) provide complementary information regarding the (13)C labeling of intermediary metabolites. Currently, these two techniques are rarely used together because of the complexity of modeling the distribution of both positional and mass isotopomers. In this study, we developed a matrix-based model for the assessment of (13)C label distribution in the tricarboxylic acid cycle and related metabolites.