Increased cough sensitivity in <i>Ttll1</i>^−/− mice.

Wild-type (WT) and Ttll1−/− mice were nebulized with saline and capsaicin (10 and 50 μM). A graph displaying the increased number of coughs (post-treatment–pretreatment). Even low doses (10 μM) of capsaicin increased the number of coughs in the Ttll1−/− mice but not in the WT mice. High doses (50 μM) of capsaicin increased the number of coughs in the WT and Ttll1−/− mice. (n = 5 mice per group; mean ± SEM; *P < 0.05, the increased numbers of coughs were compared between the WT and Ttll1−/− mice; †P < 0.05 and ‡P < 0.01, the increased numbers of coughs in comparison with those induced by saline; Mann–Whitney U-test).