A POSSIBLE ROLE FOR LIPOXYGENASE PRODUCTS AS REGULATORS OF AIRWAY SMOOTH MUSCLE REACTIVITY

The size of guinea‐pig isolated tracheal contractions induced by histamine was substantially augmented by pretreatment with the cyclo‐oxygenase inhibitor, indomethacin. However, compounds which inhibit both the cyclo‐oxygenase and lipoxygenase pathways of arachidonic acid metabolism not only did not augment histamine‐induced contractions of the guinea‐pig trachea, but also completely reversed the increased reactivity to histamine produced by indomethacin. The SRS‐A (slow reacting substance of anaphylaxis) antagonist, FPL55712, and the Antiallergic drug, cromoglycate, had no effect on the augmentation of histamine‐induced contractions by indomethacin.