Fig. 8. Effects of ketamine perfusion at room temperatures (21–23°C) upon somatic action potentials from representative C-type (0.7 m/s, A , 100 μm) and A-type (14.2 m/s, B , 300 μm) nodose neurons within the intact ganglia. The action potential waveshape of C-type neurons was reduced and broadened almost immediately upon ketamine perfusion, while that of A-type cells was unchanged following 5 min of ketamine perfusion. For all recordings, monophasic constant current pulses (< 500 μs) of fixed magnitude were applied through the patch recording electrode (arrow) from a membrane potential adjusted to −60 mV (dashed line) via  continuous direct current injection through the recording electrode.