CHANGES IN AIRWAY-RESISTANCE INDUCED BY NASAL INHALATION OF COLD DRY,DRY, OR MOIST AIR IN NORMAL INDIVIDUALS

Nasopulmonary bronchomotor reflexes elicited by mechanical or irritant stimulation of the nose have been described in animals and asthmatic patients. However, few studies were devoted to the consequences of nas al breathing of cold and dry air or of only dry or only moist air on t he bronchomotor control in normal individuals. The present study repor ted changes in interruption resistance (Rint) measured during eupneic breathing of moderately cold (-4 or -10 degrees C) and dry [0.3% relat ive humidity (RH)] air or of room air at 23 degrees C that is either d ry (0.3% RH) or moist (97% RH). Nasal inhalation of cold (-4 degrees C ) dry air or of only dry air significantly increased baseline Rint val ue (17 and 21%, respectively) throughout the 15-min test periods. The response to cold was significantly accentuated when the air temperatur e was lowered to -10 degrees C (42%). After nasal anesthesia or inhala tion of a cholinergic antagonist, cold air did not induce a change in Rint. Nasal inhalation of moist room air had no effect. No Rint change s were measured during oral breathing of the three test agents. It is concluded that the activation of cold receptors or osmoreceptors in th e nasal mucosa induces protective bronchoconstrictor responses in norm al individuals.