Effects of gossypol on guinea pig airway responsiveness: in vitro and in vivo studies

The actions of the naturally occurring polyphenol, gossypol, on guinea pig lung parenchymal strip preparations, bronchoconstriction in anaesthetized guinea pigs and platelet aggregation were examined. At concentrations between 0.2 and 20 μg/ml gossypol markedly inhibited contraction of lung parenchymal strips induced by LTB4 and LTD4, but was less effective against histamine-induced contraction. Gossypol also inhibited contraction induced by platelet-activating factor-acether (PAF-acether) but was not as effective as BN52021, a specific PAF-acether antagonist. In addition, gossypol failed to antagonize PAF-acether-induced bronchoconstriction in anaesthetized guinea pigs or the histamine-dependent bronchoconstriction response to ovalbumin in passively sensitized animals. Gossypol was minimally effective in inhibiting PAF-acether-induced platelet aggregation. This polyphenol displays a similar spectrum of effects to the radical scavenger NGDA, suggesting that, in common with other phenolic antioxidants, it may interfere with the formation of cyclo-oxygenase products in the guinea pig lung.