Figure 7. Application of 5-HT to the spinal cord evokes a 4-AP-sensitive current in spinal axons.

Giant axons were recorded under voltage clamp and 5-HT applied from a pressure ejection pipette placed over the spinal cord (the pipette contained 300 μm 5-HT). Pressure application (200 ms at the time indicated by the arrowhead) of 5-HT led to an outward current at -70 mV (A) and an inward current at -110 mV (B). The current was blocked by bath application of 4-AP (30 μm; C). D, plot of the amplitude of the 5-HT evoked current against holding potential.