FIGURE 1.

Effects of a cold environment on cough reactivity to inhaled cinnamaldehyde, and substance P levels or cell differential counts in the bronchoalveolar lavage fluid (BALF) of guinea pigs. (A) Repetitive inhalation of citric acid (model) markedly increased the number of cough events, as compared with the healthy group (control). Cough hyperreactivity was further aggravated when the whole body (model, whole-body exposure) or trunk-limbs (model, trunk-limb exposure), but not the head (model, head exposure) of guinea pigs with cough were exposed to a cold environment. In contrast, cough reactivity showed no change in healthy guinea pigs, following exposure to a cold environment (control, whole-body exposure), when they were completely exposed to a cold environment. (B) Substance P levels in the BALF of guinea pigs were increased in a similar pattern to the changes observed in cough reactivity, as presented in panel (A). (C) A significant positive correlation was noted between substance P levels in BALF and cough reactivity in the guinea pigs with cough (model). (D) Repetitive inhalation of citric acid significantly increased the percentages of neutrophils and eosinophils in the BALF. Results are presented as the mean ± SD (n = 10; *p < 0.05, **p < 0.01),