The posterior nasal nerve plays an important role on cardiopulmonary reflexes to nasal application of capsaicin, distilled water and l-menthol in anesthetized dogs

The sensory innervation of the cardiopulmonary reflexes to nasal applicatio n of capsaicin (CAPS), distilled water (DW) and l-menthol (LM) was studied in anesthetized dogs breathing through tracheostomy. A marked cardiopulmona ry reflex was observed by CAPS and DW into the nasal cavity, while a prolon gation of expiration was induced by LM. Ail these reflexes were significant ly decreased by bilateral section of the posterior nasal nerve (PNN) and co mpletely abolished by topical nasal anesthesia with Lidocaine. Responses of the whole nerve activity of the PNN to these substances corresponded to th e magnitude of the reflexes. These results indicate that PNN afferents play an important role on the reflex elicitation of the noxious, water and cold stimuli from the nasal cavity.