Influence of xanthine derivatives on cough and airway reactivity in guinea pigs.

Xanthine derivatives may inhibit phosphodiesterases without selective action on their single isoforms. In this study, effects of theophylline and theobromine on cough and airway reactivity were evaluated in awake guinea pigs using double-chamber whole body plethysmograph. Pre-treatment with theophylline and theobromine (10 mg/kg, i.p.) decreased the number of cough efforts evoked by inhalation of citric acid aerosol (0.6 mol/l) in both healthy and ovalbumin-sensitized animals. Theophylline and theobromine decreased in vivo airway reactivity, i.e., specific airway resistance measured after nebulization of citric acid and histamine aerosol (10(-6) mol/l), only in ovalbumin-sensitized animals, whereas in vitro reactivity to cumulative doses of histamine and acetylcholine (10(8)-10(-3) mol/l) measured in organ chambers significantly decreased in both healthy and ovalbumin-sensitized animals, with more pronounced effect in the latter group. In conclusion, administration of theophylline and theobromine influenced the cough and airway reactivity in ovalbumin-sensitized guinea pigs, indicating the anti-inflammatory potential of xanthine derivatives.