Comparative effects of lingual and facial nerve stimulation on intracranial and extracranial vasomotor responses in anesthetized cats.

Electrical stimulation of the central cut end of the lingual nerve (as reflex activation of parasympathetic nerve) or of the peripheral cut end of the facial (VIIth cranial) nerve (as direct activation of parasympathetic nerve) elicited the ipsilateral blood flow increases in lower lip, palate and common carotid artery (CCA) but not in frontal cerebral cortex in alpha-chloralose-urethane anesthetized, vago-sympathectomized cats. No significant difference, in terms of the vasomotor changes examined, was found between lingual nerve and facial nerve stimulation. The results suggest that there is no somato-parasympathetic reflex vasodilator mechanism serving the frontal cerebral cortex, and that changes in CCA blood flow should not be taken to be indicative of blood flow changes in cerebrocortical blood flow. However, we cannot entirely rule out the possibility of a neurogenic vasodilator influence of the facial pathway, since small blood flow increases in the frontal cerebral cortex were sometimes observed on facial nerve stimulation.