Substance P-immunoreactive boutons closely appose inspiratory protruder hypoglossal motoneurons in the cat

In anesthetized cats, we recorded intracellularly from 26 hypoglossal moton eurons which were antidromically activated following electrical stimulation of either the medial or lateral branches of the hypoglossal nerve. Twenty- one of these neurons were protruder motoneurons 6 of which had inspiratory activity. Three of the protruder motoneurons with inspiratory activity were filled with Neurobiotin and found to be closely apposed to substance P-lik e immunoreactive nerve terminals. (C) 1999 Elsevier Science B.V. All rights reserved.