THE UPTAKE OF LI-N1-ASTROCYTOMAS USING LI-7 NMR-SPECTROSCOPY( INTO HUMAN 1321)

The uptake of Li+ ions into human 1321 N1 astrocytomas cultured on the surface of microcarrier beads was followed by Li-7 NMR spectroscopy. The intracellular and extracellular Li-7 resonances were separated by the use of dysprosium tripolyphosphate as a shift reagent. Excellent s pectra were obtained from which the uptake of Li+ was found to be appr oximately ten times faster than that into human erythrocytes using the same technique and a steady-state intracellular Li+ concentration was observed within 60 min. The low intracellular Li+ concentration attai ned, relative to the extracellular concentration, indicates the presen ce of an efflux mechanism in astrocytomas that actively transports Li against its concentration gradient. The intracellular volume was esti mated by quantitative Na-23 NMR spectroscopy and the viability of the cells was confirmed by P-31 NMR spectroscopy.