Electrical and anatomic characteristics of cells of ferret paratracheal ganglion.

A preparation has been developed for study of the electrical properties of the neurons of the ferret paratracheal ganglia. Two cell types were identified. AH cells were characterized by the presence of a single action potential in response to cathodal current pulses, followed by a profound after hyperpolarization that lasted for several hundred milliseconds. Electrical stimulation of branches of the laryngeal nerves produced a fast excitatory postsynaptic potential (EPSP) that was often followed by an apparent inhibitory postsynaptic potential (IPSP). A similar response was seen with electrical stimulation of interganglionic nerve trunks. Hexamethonium reversibly inhibited fast EPSPs in these cells. Type B cells could not be excited by intracellular current injections. At least some of these cells appear to be neurons as electrical stimulation of nerve trunks resulted in a slow EPSP and, rarely, a fast IPSP. Ganglia have between 10 and 20 cell bodies, and their diameters are between 15 and 40 microns. Two types of nerve endings were seen: 1) those with mainly round agranular vesicles 50-60 nm in diameter, and 2) those with large dense-cored vesicles of approximately 100 nm with an electron-lucent halo around the core.