Effects of leukotrienes on isolated guinea-pig pulmonary arteries

Leukotrienes C4 (LTC) and D4 (LTD) produced contractions of the isolated guinea-pig pulmonary arteries, but were much less potent in these segments than in the isolated trachea and parenchymal strip from the same species. Among the arterial segments, the leukotrienes were more effective in contracting the distal end of the main pulmonary artery than the arterial branches. FPL55712 was an effective competitive antagonist of LTC, but not LTD, in the arterial segments. The data suggest that the pulmonary arteries may possess leukotriene receptors which differ from those of airway smooth muscle.