MK 287: a potent, specific, and orally active receptor antagonist of platelet-activating factor.
J Lipid Mediat
; 7(2): 115-34, 1993 Jun.
Article
in En
| MEDLINE
| ID: mdl-8400114
ABSTRACT
MK 287 (L-680,573), a tetrahydrofuran analog, potently inhibited [3H]C18-PAF binding to human platelet, polymorphonuclear leukocyte (PMN) and lung membranes with K1 values of 6.1 +/- 1.5, 3.2 +/- 0.7, and 5.49 +/- 2.3 nM, respectively. The inhibitory effects are stereospecific and competitive. The racemate, L-668,750 is less potent and the enantiomer, L-680,574 is 20-fold less potent than MK 287. Inhibition of the binding of [3H]C18-PAF to human PMN membranes by MK 287 was associated with the reduction of the affinity of the radioligand but not the number of the receptor sites. Binding of other radioligands (e.g., LTB4, LTC4, C5a, FMLP) to their specific receptors was unaltered at 1-10 microM MK 287. [3H]MK 287 bound to membranes from human platelets and PMNs KD = 2.1 +/- 0.6 and 2.9 +/- 1.2 nM, respectively. When examined on isolated human cells, MK 287 potently and selectively inhibited PAF-induced aggregation of platelets in plasma (ED50 = 56 +/- 38 nM) or gel-filtered platelets (ED50 = 1.5 +/- 0.5 nM) and elastase release from PMNs (ED50 = 4.4 +/- 2.6 nM). In studies in vivo, MK 287 inhibited PAF-induced lethality in mice (ED50 = 0.8 mg/kg orally) and PAF-induced bronchoconstriction in guinea pigs (ED50 = 0.18 mg/kg intraduodenally and 0.19 mg/kg intravenously). Inhibition of PAF-induced bronchoconstriction was accompanied by parallel rightward shifts in concentration-response curves for PAF-induced platelet aggregation measured ex vivo.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Platelet Aggregation Inhibitors
/
Platelet Membrane Glycoproteins
/
Receptors, Cell Surface
/
Receptors, G-Protein-Coupled
/
Furans
Type of study:
Diagnostic_studies
Limits:
Animals
/
Humans
Language:
En
Journal:
J Lipid Mediat
Journal subject:
BIOQUIMICA
Year:
1993
Document type:
Article