ABSTRACT
AIM: To investigate the effects of selective phosphodiesterase 3 inhibitor olprinone on cough response in guinea pigs sensitized and challenged with ovalbumin. METHODS: Forty sensitized guinea pigs were randomly divided into control ( n = 10), challenged ( n = 10), olprinone ( n = 10) and aminophylline group ( n = 10 ). Two hours after challenged with the aerosol of 1% ovalbumin or saline, animals were intraperitoneally injected either with saline,25 mg/kg of olprinone or 25 mg/kg aminophylline. At 24 h, the injection was repeated with 2. 5 mg/kg and 25 mg/kg olprinone or 2. 5 mg/kg and 25 mg/kg aminophylline respectively in olprinone and aminophylline group, cough response to inhaled capsaicin and airway responsiveness to methacholine (PC150) were measured. Then, total cell number and differential counts were analyzed in bronchoalveolar lavage fluid. RESULTS: The cough frequency was (5 ± 2) times/3 min in control group and (24 ± 3 ) times/3 min in challenged group ( P ＜ 0. 05 ), while PC150 was (659 + 57 ) mg/L in control group and (238 + 67 ) mg/L inchallenged group ( P ＜ 0. 05 ). 25 mg/kg olprinone significantly inhibited the augmented cough response and airway hyperresponsiveness, the cough frequency and PC150 were (15 ±2) times/3 min and (580 ±45) mg/L (P ＜ 0. 05 ), which differed significantly from (18 ± 2) times/3 min and (438± 52) mg/L in aminophilline group (P ＜ 0. 05). However, olprinone failed to reverse the elevated total cell number and percentage of eosinophils in bronchoalveolar lavage fluid from guinea pigs challenged with ovalbumin (P ＞ 0. 05 ). CONCLUSION: Phosphodiesterase 3 inhibitor attenuates cough response associated with eosinophilic airway inflammation by bronchodilatory effect.
ABSTRACT
PURPOSE: Exercise-induced bronchospasm (EIB) is widely prevalent in asthmatic patients. Recently, eosinophilic airway inflammation and atopy (defined as skin sensitivity to common aeroallergens) are considered to be a important factors in the pathogenesis of asthma. Thus we studied to find out the effect of atopy and airway eosinophilic inflammation on exercise- induced bronchospasm. METHODS: We followed up the cases of 132 mild asthmatics for 2 years. On their first visit, skin prick tests, with 29 common allergens including dust mites antigen, and sputum induction were performed. And 3 days later, methacholine challenge was done. 24 hours after methacholine challenge, treadmill test was performed and the positive EIB was defined as a 15% reduction or more in FEV1 from baseline after exercise. RESULTS: EIB was observed in 54 (40.9%) of 132 asthmatic subjects. There was no significant difference in atopy between EIB positive and EIB negative asthmatics. Eosinophil and eosinophil cationic protein in induced sputum were significantly higher in EIB positive asthmatics. We also found the significant correlation between bronchial responsiveness (BR) index and maximal % fall in FEV1. CONCLUSION: The severity of bronchospasm evoked by exercise was more closely related to eosinophilic airway inflammation and airway hyperresponsiveness to methacholine than atopy.