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 anti-allergic drug, cromoglycate, had no effect on the augmentation of histamine-induced contractions by indomethacin.