Biomedical applications of ¹³³Cs NMR

¹³³Cs NMR is a valuable tool for non-invasively probing biological systems. As a congener of potassium, it accumulates in the intracellular space, primarily through the action of the Na⁺-K⁺ pump (ATPase). In addition, it is possible to resolve the MR signal of ¹³³Cs in different tissue compartments on the basis of chemical shift or MR relaxation properties. This compartmental resolution applies not only to the intra- and extracellular spaces, but to subcellular compartments as well. In this review, we discuss the studies defining the ion transport, chemical shift and relaxation characteristics of ¹³³Cs in living systems. We also review the application of ¹³³Cs NMR to evaluation of ion transport across membranes and the kinetic/chemical environment of the intracellular space in systems ranging from red blood cells to rat brain.