Measurement of intracellular sodium with NMR methods

The measurement and monitoring of intracellular sodium concentrations is critically important to elucidating normal and abnormal cellular physiology. NMR approaches to this problem using 23 Na NMR spectroscopy have included detailed analysis of relaxation time constants, the use of chemical shift agents, and detection of multiple‐quantum‐filtered signals. These methods have been applied to isolated cells as well as to perfused organs and in situ tissues. The theoretical framework for as well as the practical applications and limitations of these methods are discussed.