Membrane properties of preganglionic fibers occurred in bullfrog lumbar sympathetic ganglion.

Membrane properties of preganglionic fibers in the bullfrog lumbar sympathetic ganglion were studied using a conventional intracellular microelectrode technique. Charging or discharging electrotonus of the preganglionic fibers were found to be slow. The slow and fast time constants were around 62 and 15 msec, respectively. An inward-going rectification was activated in the potential range below -80mV. These electrophysiological properties differed from those observed in a principal neuron and suggested a close resemblance between the sympathetic preganglionic fibers and thick myelinated fibers.