Regional sensitivity of the respiratory tract to stimuli causing cough and reflex bronchoconstriction.

Sensory nerves mediating cough and reflex bronchoconstriction have a non-uniform distribution in the respiratory tract. Afferent nerves originating in the laryngeal region differ from those of the intrapulmonary airways in their responsiveness to physical events in the breathing cycle and to chemical stimuli. Also, within each site afferents with separate characteristics are present. Studies in animals and human subjects have shown that the larynx and the carina are particularly sensitive to mechanical stimuli, whereas the intrapulmonary airways seem to be more sensitive to mediators and irritants. Based on recent data, the importance of the intrapulmonary airways to mediator/irritant-induced cough and reflex bronchoconstriction is emphasized. Inferentially, drugs inhibiting afferent neural activity arising in intrapulmonary airways would be a novel possibility in the treatment of cough and reflex bronchoconstriction.