Leukotrienes mediate tracheal hyperresponsiveness after nitric oxide synthesis inhibition

Preincubation of guinea pig tracheas with the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 120 microM) resulted in a significant upward shift of the histamine concentration-response curve with a concomitant inhibition of prostaglandin E2 production. Preincubation of the preparations with a 5-lipoxygenase inhibitor (AA-861, 2-(12-hydroxy-5,10-dodecadiynyl)-3,5,6-trimethyl-p-benzoquinone) or a leukotriene C4,D4,E4 receptor antagonist (FPL 55712, sodium 7-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-2-hydroxy propoxy]-4-oxo-8- propyl-4H-1-benzopyran-2-carboxylate) totally blocked the L-NAME-induced tracheal hyperresponsiveness. A shift from cyclo-oxygenase to Lipoxygenase products, in particular leukotrienes, is likely to be responsible for the L-NAME-induced tracheal hyperresponsiveness.