In vivo activity of tracheal parasympathetic ganglion cells innervating tracheal smooth muscle.

In vivo intracellular recording and intrasomal injection of Lucifer yellow revealed two populations of postganglionic parasympathetic neurons in the tracheal ganglia of cats. One consisted of large cells that had an inspiratory rhythm, had a significant post-spike afterhyperpolarization, and projected to the tracheal smooth muscle. The second consisted of small cells that fired with an expiratory rhythm, had no significant afterhyperpolarization, and projected to the intercartilaginous spaces.