Characterization of a leukotriene D4 receptor in guinea pig lung.

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[3H]Leukotriene D4 was found to bind, in a saturable manner and with exceedingly high affinity, to a membrane preparation from guinea pig lung. Measurement of saturation at equilibrium yielded Kd values of 5.46 +/- 0.31 X 10(-11) M at 20 degrees C and 2.12 +/- 0.37 X 10(-10) M at 0 degree C while the numbers of binding sites (Bmax) were 384 +/- 34 and 302 +/- 44 fmol/mg of protein at 20 and at 0 degree C, respectively. The time courses of both association and dissociation were slow but the rate of dissociation was accelerated by either NaCl or GTP. Binding was enhanced by Ca2+, Mg2+, and Mn2+ and inhibited by Na+ but not by Li+ or K+, suggesting that the binding of leukotriene D4 may be regulated by ions. Leukotriene E4, but not leukotriene C4, had a high affinity for the putative receptor, consistent with the pharmacological evidence that the actions of leukotrienes D4 and E4 are mediated by a receptor distinct from that for leukotriene C4. Affinities of stereoisomers and related compounds for the leukotriene D4 binding sites closely paralleled their contractile activities in guinea pig lung parenchymal strips. In addition, the antagonist of slow-reacting substance of anaphylaxis, FPL 55712, inhibited the binding of [3H]leukotriene D4 with a Ki value of 1 X 10(-7) M, which is in agreement with reported Kb values obtained in pharmacological studies.

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