Inhibition of arachidonic acid-induced contraction of guinea pig lung strips.

The effects of several enzyme inhibitors on arachidonic acid-induced contractions of guinea pig lung strips were studied. Varying concentrations of indomethacin, an inhibitor of cyclo-oxygenase, produced only a limited effect on contraction of tissue strips. By contrast, nordihydroaguaiaretic acid (NDGA), 5,8,11,14-eicosatetraynoic acid (ETYA), and phenidone, which inhibit either lipoxygenase, or both antagonism of the arachidonic acid-induced contraction. The effects of these latter agents were similar to that of FPL 55712. Results indicate that the products of cyclooxygenase are predominantly involved in the early phase and the products of lipoxygenase are predominantly related to the late phase of arachidonic acid-induced contraction.