Comparative activity of leukotriene D4, 5,6-dihydroxy-eicosatetraenoic acid and lipoxin A on guinea pig lung parenchyma and ileum smooth muscle.

Various compounds derived from the 5-lipoxygenase pathway of arachidonic acid (Leukotriene D4 [LTD4], 5S,6R-dihydroxy-7,9,11,14- eicosatetraenoic acid [5S,6R-DiHETE], 5S,6S-DiHETE, 5S,6R-Lipoxin A [5S,6R-Lx A], 5S,6S-Lx A) were tested on guinea-pig lung parenchyma strips (G.P.L.P.S.) and ileum smooth muscles (G.P.I.S.M.) mounted in a cascade superfusion system. These products induced contractile responses on G.P.L.P.S., whereas only the LTD4 was active on G.P.I.S.M. FPL-55712 inhibited almost totally their myotropic activity. The 5S,6R compounds were more active than the 5S,6S ones, with an order of potency of LTD4 greater than 5,6-DiHETE greater than Lx A. It is suggested that 5,6-DiHETE and Lx A isomers may act via the lung LTD4 receptors which appear less specific than ileum LTD4 receptors.