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 greater than leukotriene E4 much greater than arachidonic acid, and for their contractile effect on lung strips was leukotriene C4 = leukotriene D4 = leukotriene E4 much greater than 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.