FASTER VOLTAGE-DEPENDENT ACTIVATION OF NA-115 CELLS( CHANNELS IN GROWTH CONES VERSUS SOMATA OF NEUROBLASTOMA N1E)

Kinetics of voltage-gated ionic channels fundamentally reflect the res ponse of the channels to local electric fields. In this report cell-at tached patch-clamp studies reveal that the voltage-dependent activatio n rate of sodium channels residing in the growth cone membrane differs from that of soma sodium channels in differentiating N1E-115 neurobla stoma cells. Because other electrophysiological properties of these ch annels do not differ, this finding may be a reflection of the differen ce in intramembrane electric field in these two regions of the cell. T his represents a new mechanism for channels to attain a range of activ ities both within and between cells.