Modification of human airway smooth muscle reactivity by drugs that interfere with arachidonic acid metabolism.

Histamine-induced contractions of small airways from human lung were substantially augmented by the cyclo-oxygenase inhibitor, indomethacin, whereas the contraction of larger airways was not. Mixed cyclo-oxygenase/lipoxygenase inhibitors of arachidonic acid metabolism did not modify histamine-induced contractions of smooth muscle from either small or large airways but completely reversed the augmentation of histamine responses produced by indomethacin on the smaller airways. The SRS-A (slow reacting substance of anaphylaxis) antagonist, FPL55712, did not affect the augmentation of histamine-induced contractions by indomethacin.