Comparison of the use of gel threads and microcarrier beads in Li+ transport studies of human neuroblastoma SH-SY5Y cells

We have applied Li-7 NMR spectroscopy coupled with continuous perfusion to study Li+ transport into SH-SY5Y human neuroblastoma cells. Two methods commonly used in the immobilization of cells, namely entrapment in gel threads and anchorage on microcarrier beads, were used in this study. We were able to differentiate between intra- and extracellular Li-7 NMR resonances in the presence of 3 mM HTm(DOTP)(4-) as the shift reagent, irrespective of the mode of cell immobilization. Two different types of gel threads, agarose and Matrigel, were used. To determine the optimum diameter of the threads required for this type of study, agarose threads of three different diameters were used. Our results indicate that agarose threads gave a first-order rate constant similar to that obtained for Biosilon microcarrier beads. The rate constant for Li+ influx was found to decrease with increasing thread diameter and with cells entrapped in Matrigel threads. Addition of the Li+ ionophore DB14C4 was previously shown to increase the rate of Li+ influx into human RBCs and this effect was also observed in neuroblastoma cells with an increase in the pseudo-first-order rate constant of Li+ uptake by a factor of two.