Biotransformation and excretion: in vivo studies utilizing stable isotopes and nuclear magnetic resonance

Specific 13C labeling in combination with nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for the study of metabolism. Nuclear magnetic resonance allows both the extent and distribution of 13C labels in metabolites to be quantified without the need to isolate or degrade them. In addition, NMR is nonperturbing to living cells, allowing real-time observation of metabolic processes. To date, the application of 13C-NMR to in vivo studies has been confined to the study of metabolic processes in cell suspensions, perfused organs, and small animals. The continuing development of large-bore high field magnets and surface coils will, in principle, allow in vivo metabolic studies to be extended to humans.