Formation of oedema and accumulation of eosinophils in the guinea pig lung. Inhibition by inhaled beta-stimulants.

The action of the two beta-stimulants fenoterol and SOM 1122 (alpha-[[[3-(1-benzimidazolyl)-1, 1-dimethylpropyl]amino]methyl]-2-fluoro-4-hydroxybenzyl alcohol methane sulfonate) against inflammatory correlates of bronchial asthma was investigated by performing the following experiments: Passively sensitized guinea pigs were challenged by antigen aerosol under protection of mepyramine. The animal response was a 5- to 6-fold increase in the number of eosinophils in the bronchoalveolar lavage fluid after 1 or 2 days. In addition, increased microvascular permeability was elicited in guinea pig lungs after inhalation of a low concentration of histamine for 60 min. Both inflammatory reactions were inhibited by inhalation of remarkably low concentrations (0.004-0.04%) of the two beta-stimulants. These concentrations were 5 to 75 times lower than the EC50 values required for inhibition of acetylcholine-induced bronchoconstriction in the same species. The lung eosinophilia was not modified by inhibitors of lipoxygenase or cyclo-oxygenase.