Sensitivity of the resting sodium conductivity of leech retzius nerve cells to tetrodotoxin

Abstract

1. 1. Simultaneously, the effect of sodium-free medium and tetrodotoxin (3 × 10 −8 M/ml) were investigated on some passive electrophysiological properties of leech Retzius nerve cells. 2. 2. Complete replacement of Na + with Tris or addition of tetrodotoxin to the leech Ringer was followed by an increase of input resistance in contrast to the cell-to-cell interaction which was not affected by such a procedure. 3. 3. At the same time tetrodotoxin was not able to block repetitive spike activity. 4. 4. The data imply the existence of two types of Na + channel in leech Retzius nerve cells.