Inhibition by CV-3988 of the binding of [3H]-platelet activating factor (PAF) to the platelet

Biochem Pharmacol. 1985 May 1;34(9):1491-5. doi: 10.1016/0006-2952(85)90689-6.


The inhibitory effects of CV-3988, a specific antagonist of PAF, on the binding of [3H]-PAF to washed platelets of various species including human were examined. The dissociation constant (Kd), binding capacity (Bmax), and the number of receptor/platelet for the specific binding site of rabbit platelets were 2.2 +/- 0.2 nM, 93.7 +/- 8.3 fmoles/10(8) platelets, and 568 +/- 50, respectively. CV-3988 selectively inhibited the specific binding of [3H]-PAF to rabbit platelets with an IC50 of 7.9 X 10(-8) M, and it slightly increased the Kd value (2.5 +/- 0.8 nM) and decreased the binding capacity for PAF (Bmax: 54.3 +/- 16.3 fmoles/10(8) platelets). The Ki value of CV-3988 for the specific binding of [3H]-PAF to rabbit platelets was 1.2 X 10(-7) M. CV-3988 had no effects on the binding of [3H]-5-hydroxytryptamine (5-HT) to rabbit platelets and on the shape change of the platelet induced by 5-HT. CV-3988 also inhibited the specific binding of [3H]-PAF to human and guinea-pig platelets with IC50 values of 1.6 X 10(-7) and 1.8 X 10(-7) M, respectively. CV-3988 inhibited the PAF-induced aggregation in rabbit, guinea-pig, and human platelets. These findings show that CV-3988 is a specific antagonist of PAF at the receptor site(s) of platelets and, in these species, inhibits PAF-induced platelet aggregation by inhibiting the binding of PAF to the "PAF receptor". No specific binding of [3H]-PAF to the platelet of rats and mice was observed, indicating that these species lack a PAF receptor.

MeSH terms

  • Animals
  • Blood Platelets / cytology
  • Blood Platelets / metabolism*
  • Depression, Chemical
  • Guinea Pigs
  • Humans
  • In Vitro Techniques
  • Male
  • Mice
  • Phospholipid Ethers*
  • Platelet Activating Factor*
  • Platelet Aggregation / drug effects
  • Platelet Membrane Glycoproteins*
  • Rabbits
  • Rats
  • Receptors, Cell Surface / analysis
  • Receptors, G-Protein-Coupled*
  • Serotonin / metabolism
  • Serotonin / pharmacology
  • Species Specificity
  • Thiazoles / pharmacology*
  • Tritium


  • Phospholipid Ethers
  • Platelet Activating Factor
  • Platelet Membrane Glycoproteins
  • Receptors, Cell Surface
  • Receptors, G-Protein-Coupled
  • Thiazoles
  • platelet activating factor receptor
  • Tritium
  • Serotonin
  • CV 3988