Asymmetry in reflex responses of nasal muscles in anesthetized guinea pigs.

Nasal reflexes elicited by mechanical or electrical stimulation of nasal afferents were studied in anesthetized guinea pigs. Probing the nasal cavity of one side evoked a greater activation of the contralateral than the ipsilateral nasal muscles and, occasionally, sneezing. Similarly, electrical stimulation of the ethmoidal nerve often caused sneezing, with a greater activation of the nasal muscles and a greater increase in resistance on the contralateral side. Asymmetrical activation of the nasal muscles in response to mechanical stimuli induces asymmetrical airflows, especially during sneezing, between the two sides of the nasal cavity. Most of the expired air is forcibly blown out through the ipsilateral nostril, thus improving the elimination of irritants from the nose.