EFFECTS OF ISOZYME-SELECTIVE PHOSPHODIESTERASE INHIBITORS ON EOSINOPHIL INFILTRATION IN THE GUINEA-PIG LUNG

The effects of selective phosphodiesterase isozyme inhibitors on eosin ophil infiltration induced by antigen challenge or by exposure to an a erosol of platelet-activating factor (PAF) were investigated in the gu inea-pig. Pretreatment 24 h and 3 h before antigen challenge or PAF ex posure with theophylline (100 mg/kg), rolipram (5 mg/kg) and Ro 20-172 4 (30 mg/kg) significantly reduced the increase in eosinophil numbers in bronchoalveolar lavage fluid. In contrast, milrinone, SK&F 94-120 a nd zaprinast were ineffective against antigen-induced eosinophil recru itment. Theophylline, rolipram and Ro 20-1724 also significantly reduc ed the release of eosinophil peroxidase into the bronchoalveolar lavag e fluid. It is suggested that inhibitors of type TV phosphodiesterase have anti-inflammatory effects in the airways and may be useful in the treatment of asthma.