Involvement of prostanoids in the pulmonary pressor effect of histamine

The role of prostanoids in the pulmonary actions of histamine(HA) was investigated using various antagonists and assay organs in superfusion cascade. Intraarterial injection of HA to the perfused lung caused contractions of rabbit aorta, rat stomach strips, guinea pig trachea, but contraction followed by relaxation of bovine coronary artery, superfused with lung effluent. Lung effluent produced no significant changes in resting tensions of guinea pig ileum or rat colon. The thromboxane synthetase inhibitor, UK 38485, reduced and the thromboxane/prostaglandin receptor antagonist, SQ 29548 abolished HA-induced contractions of all superfused assay tissues. Both contractile and relaxant responses of bovine coronary artery were completely inhibited by indomethacin. The pulmonary pressor effect of HA was also significantly inhibited by all of these antagonists. Our results indicate that HA releases thromboxane A2, prostaglandin endoperoxides, and prostacyclin but not leukotriene and prostaglandin E2- like substances from the guinea pig lung.