INTRACELLULAR LITHIUM - STUDIES USING LI-7 NUCLEAR-MAGNETIC-RESONANCESPECTROSCOPY IN ERYTHROCYTES, HEPATOCYTES, AND FIBROBLASTS

Intracellular lithium concentrations have been determined in isolated human erythrocytes, isolated rat hepatocytes and in cultured Swiss Mou se 3T3 fibroblasts. Li-7 Nuclear Magnetic Resonance Spectroscopy (NMR) was used to determine intracellular lithium using dysprosium tripolyp hosphate as a shift reagent to distinguish the intracellular from the extracellular signal. The results indicate that lithium concentrations within the cells studied are considerably lower than had been presume d hitherto, usually less than 10 % of the external lithium concentrati on (0 - 40 mmol.l-1). These findings are discussed in relation to the proposed mode of action of lithium in recurrent affective disorders, a nd in particular those theories involving triphosphoinositide metaboli sm, whose enzymes have been shown to be inhibited by lithium.