(R,R)-MK 287

(R,R)-MK 287 (L-680574) is a tetrahydrofuran derivative that potently inhibits the binding of [3H]C18-PAF to human platelets, polymorphonuclear leukocytes (PMNs), and lung membranes with Ki values of 6.1, 3.2, and 5.49 nM, respectively. (R,R)-MK 287 potently and selectively inhibits PAF-induced platelet aggregation (ED50=56 nM) and elastase release from PMNs (ED50=4.4 nM). (R,R)-MK 287 inhibits PAF-induced lethality in mice (ED50=0.8 mg/kg, po) and PAF-induced bronchospasm in guinea pigs (ED50=0.18 mg/kg).