LI-7 AND NA-23 NMR-STUDIES OF TRANSMEMBRANE CATION-TRANSPORT MEDIATEDBY IONOPHORE LASALOCID-A

Ion transport across phospholipid vesicles was studied by Li-7 and Na- 23-NMR using an aqueous anionic paramagnetic shift reagent, dysprosium nitrilotriacetate [Dy(NTA)(2)](3-), mediated by ionophores, lasalocid A and A23187. The intra-and extracellular Li-7 and Na-23-NMR signals were well separated (20 Hz) at mM concentration of the shift reagent. The observed data on the rate constant for lithium transport across DP PC vesicles at various concentrations of the ionophores indicated that lasalocid A is a more efficient carrier for lithium ion compared with the sodium ion transport by this ionophore, while A23187 was not spec ific to either of the ions (Li or Na). (C) 1998 European Peptide Socie ty and John Wiley & Sons, Ltd.