Steady-state properties of sodium channels from healthy and tumorous human brain.

This extensive bilayer study of unpurified human brain channels from non-diseased and tumorous human brain involves more than 300 lipid bilayer experiments. Single channel conductances and subconductances, single channel fractional open times, the voltage-dependence of tetrodotoxin (TTX) block and the steady-state activation behavior of four different human brain synaptosomal preparations have been examined. Reproducible values have been obtained for the molecular electrophysiological parameters and their standard deviations, providing a database for future comparisons involving disease or drug-related changes in molecular sodium channel functions. In comparison with sodium channels from other species and under other experimental conditions, the bilayer system proved to be a reliable experimental setting. Despite the very different histology of the tissue probes, there were no significant differences in any of the examined electrophysiological features.