Identification of leukotriene D₄ receptor binding sites in guinea pig lung homogenates using [³H]leukotriene D₄

We have characterized [³H]leukotriene D₄ binding to guinea pig lung homogenates. Both biphasic dissociation kinetics and curvilinear Scatchard plots indicated the presence of [³H]leukotriene high and low affinity states of the binding sites. The rank order of potency for the competition study was leukotriene C₄ = leukotriene D₄ leukotriene E₄ ≫ arachidonic acid, and for their contractile effect on lung strips was leukotriene C₄ = leukotriene D₄ = leukotriene E₄ ≫ arachidonic acid. FPL-55712 was the only other agent tested that inhibited binding. These results suggest that binding of [³H]leukotriene D₄ to the homogenate is consistent with its binding to specific leukotriene D₄ receptor sites.