Effect of electrical stimulation of the superior laryngeal nerve on respiratory-modulated facial nerve activity in cats

The purpose of the present study was to evaluate the response of respirtory-modulated facial nerve to electrical activation on the superior laryngeal nerve (SLN). The experiments were performed on fifteen cats which were anesthetized with pentobarbital, vagotomized, paralyzed and artificially ventilated. The animals were maintained at different levels of carbon dioxide in hyperoxia. Parameters of electrical stimulation were 20 Hz of frequency, 0.5 mSec of duration and a variety of intensity (30, 50, 100 and 150 μA). Facial activity increased significantly (P < 0.05) in response to SLN activation. This augmentation of facial discharge was proportional to the intensity of electrical activation on the SLN. Phrenic response to SLN stimulation was either decreased or not changed. Total duration of respiratory cycle after activation of the SLN was increased. The results showed that facial activity may play a role in the regulation of nasal resistance.