A 13C Isotopomer Model for Accurate NMR Quantification of Substrate Selection and Anaplerosis

Wei Li¹, Fang Bian¹, Priyanajana Chaudhuri¹, Xin Yu¹

Pyruvate carboxylation is important in energy metabolism. However, accurate quantification of pyruvate carboxylation with NMR remains to be demonstrated. In this study, a 13C isotopomer model for citrate acid cycle was developed and applied to the quantification of pyruvate carboxylation and the comparison of NMR and GC-MS. Two groups of rat hearts were perfused with buffer containing 5.5 mM glucose and 0.6 mM palmitate with either glucose or palmitate being uniformly labeled with 13C. Pyruvate carboxylation was determined from NMR analysis of experiments. NMR and GCMS were equally good in quantifying substrate utilization, but different in quantifying anaplerosis.