REFLEX ACTIVATION OF NASAL SECRETION BY UNILATERAL INHALATION OF COLDDRY AIR

Exposure to cold dry air induces rhinorrhea and other nasal symptoms i n many persons. To evaluate whether this response involves a neurogeni c component, we delivered a unilateral cold dry air (UniCDA) nasal cha llenge to volunteers with previously documented reactivity to cold dry air. We measured their nasal secretory responses bilaterally using sm all filter paper discs to absorb secretions from the nasal mucosa. Uni CDA increased nasal secretion both ipsilateral (p < 0.001) and contral ateral (p < 0.001) to the challenge when compared with control challen ge. Topical atropine (0.225 mg), a muscarinic antagonist, inhibited ip silateral secretion (p < 0.002) when given ipsilateral to UniCDA. When atropine was given contralateral to UniCDA, there was a trend toward reduction of contralateral secretion but no effect on ipsilateral secr etion. Topical anesthesia with lidocaine given ipsilateral to UniCDA i nhibited ipsilateral (p < 0.02) and contralateral (p < 0.05) secretion immediately after challenge. Topical anesthesia did not inhibit metha choline-induced nasal secretion. Thus, UniCDA stimulates reflex secret ion both ipsilateral and contralateral to challenge which is inhibitab le by interrupting either the efferent or the afferent arm of the refl ex are. This human in vivo model supports the importance of neural mec hanisms in airway responsiveness to an environmental stimulus.