Respiratory-Related Facial Nerve Activity in Response to Activation of the Rostral Ventrolateral Medulla in the Cat

The effects of electrical and chemical activation of the rostral ventrolateral medulla (rVLM) on respiratory-related facial nerve activity were investigated in decerebrated, paralyzed, vagotomized and ventilated cats. The animal was maintained at normocapnia and hypercapnia in hyperoxia. Phrenic and facial nerve activities were simultaneously recorded. Excitation of the rVLM either by electrical current (12.5 to 50 μA, 80 Hz and 0.5 ms pulse duration) or glutamate microinjection (50 mM, 20 to 200 nl) inhibited both phrenic and facial nerve discharges. Although inhibition of the rVLM upon both nerves was attenuated by hypercapnia, this inhibition remained significant during hypercapnia. These results suggest that the rVLM may be involved in the modulation of upper airway patency by controlling respiratory-related facial nerve activity.