Fig. 2.
Effects of 1 μm SCPA or 1 μm 5HT on EJPs recorded extracellularly in I3a muscle using a perfusion electrode. A, Effects of SCPs and 5HT on EJPs evoked by stimulating B38. Note that the effects of the SCPs reversed during washout, whereas those of 5HT persisted for at least 3 hr. Recordings are from different experiments. B, Cumulative results for the SCPs and 5HT on B38-evoked EJPs (n = 11). To pool results from different neuromuscular preparations, EJPs were normalized to the maximum EJP amplitude (set at 1.0). 5HT or the SCPs were applied from −20 to 0 min. Note that the effects of the SCPs reverse during washout, whereas those of 5HT persisted for at least 1 hr of washout. The small upward inflection of EJP amplitude observed at the end of 5HT perfusion suggests that 5HT may also have a small inhibitory effect that reverses during washout.