Figure 9. The effect of 5-HT on responses to repetitive stimulation.
A, a Ca2+ transient evoked by a train of 5 stimuli (arrowheads) at 50 Hz, in control (with 50 μm AP5 and 10 μm CNQX), in the presence of 30 μm 5-HT and after washout of the drug. B, a paired recording was made between a reticulospinal axon and a synaptically coupled postsynaptic neuron. EPSCs (lower traces) were evoked by repetitively stimulating the presynaptic reticulospinal axon (5 stimuli at 50 Hz). 5-HT (30 μm) reduced the EPSC amplitude of each of the chemical components. Data for each trace are the average from 12 sequentially evoked responses. The holding potential was -70 mV. The upper trace is an example of one train of presynaptic action potentials.