NMR-STUDIES OF INTRA-CELLULAR AND EXTRACELLULAR RED-BLOOD-CELL LITHIUM BY TRANSVERSE RELAXATION MEASUREMENTS AND SHIFT-REAGENTS

Lithium salts are used in the treatment and prophylaxis of bipolar or mood disorders, The mechanism of action by which the cation exerts its therapeutic influence is unknown, A knowledge of brain Li concentrati on, its distribution in the brain, and its properties in the cellular microenvironment may have a strong influence on the understanding of L i function, The differentiation of lithium in the intra and extracellu lar environments has been achieved in a noninvasive manner in red bloo d cell (RBC) model. The two distinct transverse relaxation (T-2) compo nents have been observed in the blood sample drawn from lithium treate d rats, These results indicate two different environments for Li with a fast (T-2f) and a slow (T-2s) component in the RBC model correspondi ng fractions that contribute to each relaxation component, The results compare well with the intra-and extracellular RBC lithium measured us ing shift reagents, Our studies indicate that the T-2 method has utili ty in estimating the intracellular Li in systems that exhibit similar T-2 behavior, The studies performed at different Li doses in the rat m odel indicate that the method may have utility in following a wide ran ge of intracellular Li. (C) 1998 Elsevier Science Inc.