| Abstract: | We have developed a guinea pig model for coughrelated to allergic airway inflammation. Unanesthetized animals wereexposed to capsaicin aerosols for 10 min, and cough frequency wascounted during this period. The cough evaluation was performed by the following three methods: visual observation, acoustic analysis, andmonitoring of pressure changes in the body chamber. These analysesclearly differentiated a cough from a sneeze. To elucidate therelationship between cough response and airway inflammation, animalswere immunosensitized and multiple challenged. Sensitized guinea pigspresented no specific changes microscopically, but multiple-challengedanimals showed an increased infiltration of inflammatory cells into theairway. Cough number in response to capsaicin increased significantlyfrom 4.7 ± 1.4 coughs/10 min in normal animals to 10.6 ± 2.0 coughs/10 min in sensitized animals and further to 22.8 ± 1.3 coughs/10 min in multiple-challenged animals. This augmentedcough frequency was significantly inhibited by the inhalation oftachykinin-receptor antagonists and by oral ingestion, but notinhalation, of codeine phosphate. The results suggest that airwayinflammation potentiates an elevation of cough sensitivity in this model. |
