Fig. 1.

Menthol (100 mg/kg, p.o.) inhibited coughing evoked by citric acid (CA). Control animals received the vehicle for menthol (water). Each dose of CA (0.01–0.3 M) was administered by aerosol for 5 min, with 5-min intervals in between doses. Results are presented as mean ± SE cumulative coughs evoked by the lower concentrations of CA studied (0.01–0.1 M) and mean ± SE cumulative coughs evoked by all concentrations of CA (0.01–0.3 M). *Indicates that menthol significantly inhibited the coughing evoked by CA (P < 0.05; n = 10–18).