Difference in glossopharyngeal and phrenic inspiratory activities of rats during hypocapnia and hypoxia.

Inspiratory (I) activities of glossopharyngeal (IX) and phrenic (Phr) nerves were compared during hypocapnia or hypoxia in the urethane anesthetized and carotid deafferented rat. Hypoxic or hypocapnic suppression of I activity was smaller in the IX than in the Phr nerve. A small ramp like rhythmic IX activity was seen even in the absence of Phr discharge during hypocapnia or hypoxia. Respiratory rhythmicity may be better recognized by IX motoneuron activity during suppression by altered chemical stimuli.