An intracellular investigation of cat vesical pelvic ganglia.

1. Intracellular recording techniques were used to study individual neurons in the cat parasympathetic vesical pelvic ganglion (VPG). 2. Active and passive electrical properties were determined from 140 ganglion cells (35 preparations). 3. Three types of ganglion cells were distinguished. Type I (A and B) cells were nonaccommodating cells in response to depolarizing current pulses. Type II cells showed accommodation to depolarizing current pulses. Other cells, presumably glia, were also impaled. 4. Type IB cells exhibited two kinds of nonsynaptic spontaneous activity, spontaneous action potentials (60-70 mV) and small spontaneous potentials (up to 5 mV). Characteristics of the spontaneous activity were examined. 5. The duration of the spikes' afterhyperpolarization resulting from either orthodromic or antidromic train stimulation was dependent on the frequency of train stimulation. No long-lasting posttrain hyperpolarization was observed. 6. Chlorisondamine (10(-6) M), d-tubocurarine (10(-5) M), and hexamethonium (10(-5) M) reversibly blocked orthodromic responses. 7. The VPG is a useful model to study parasympathetic ganglionic transmission at the cellular level.