PPADS (30 μM) blocks distension and electrically evoked slow EPSPs in a NOS-immunoreactive descending interneuron.

Left column shows responses to distension: the upper trace in each pair is the membrane potential, the lower trace is the time course of the applied distension. Downward deflections show the membrane potential changes produced by constant amplitude current pulses used to monitor any changes in input resistance. The right column shows responses to focal electrical stimulation (5 pulses at 10 Hz, arrow heads) applied to a circumferentially directed internodal strand. The dashed lines indicate a fast EPSP evoked by a single impulse in the train (shown with expanded time base below). The evoked slow depolarizations evoked by either stimulus were reversibly abolished by 30 μM PPADS in the recording chamber within 10 minutes of exposure.