Inhibition of cellular action of thrombin by N3-cyclopropyl-7-[[4-(1-methylethyl)phenyl]methyl]-7H-pyrrolo[3, 2-f]quinazoline-1,3-diamine (SCH 79797), a nonpeptide thrombin receptor antagonist

Biochem Pharmacol. 2000 Nov 15;60(10):1425-34. doi: 10.1016/s0006-2952(00)00460-3.


A growing body of evidence suggests an important contribution of the cellular actions of thrombin to thrombosis and restenosis following angioplasty. Recently we reported on SCH 79797 (N3-cyclopropyl-7-¿[4-(1-methylethyl)phenyl]methyl¿-7H-pyrrolo[3, 2-f]quinazoline-1,3-diamine) and its analogs as new potent, nonpeptide thrombin receptor antagonists. This study further characterizes the biochemical and pharmacological actions of pyrroloquinazoline inhibitors of protease activated receptor-1 (PAR-1) in human platelets and coronary artery smooth muscle cells (hCASMC). SCH 79797 and its N-methyl analog (SCH 203099) inhibited binding of a high-affinity thrombin receptor-activating peptide ([(3)H]haTRAP, Ala-Phe(p-F)-Arg-ChA-HArg-[(3)H]Tyr-NH(2)) to PAR-1 with IC(50) values of 70 and 45 nM, respectively. SCH 79797 inhibited [(3)H]haTRAP binding in a competitive manner. SCH 79797 and SCH 203099 inhibited alpha-thrombin- and haTRAP-induced aggregation of human platelets, but did not inhibit human platelet aggregation induced by the tethered ligand agonist for protease-activated receptor-4 (PAR-4), gamma-thrombin, ADP, or collagen. SCH 203099 inhibited surface expression of P-selectin induced by haTRAP and thrombin, and it did not increase P-selectin expression or prevent thrombin cleavage of the receptor. Thrombin and TFLLRNPNDK-NH(2) (TK), a PAR-1-selective agonist, produced transient increases in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) in hCASMC. This increase in [Ca(2+)](i) was inhibited effectively by SCH 79797. However, the Ca(2+) transients induced by SLIGKV-NH(2,) a PAR-2-selective agonist, were not inhibited by SCH 79797. Thrombin- and TK-stimulated [(3)H]thymidine incorporation also was inhibited completely by SCH 79797. The results of this study demonstrate that SCH 79797 and SCH 203099 are potent, selective antagonists of PAR-1 in human platelets and hCASMC. These data also suggest that the thrombin stimulation of Ca(2+) transients and mitogenesis in hCASMC is mediated primarily through activation of PAR-1.

MeSH terms

  • Apoptosis Regulatory Proteins
  • Bacterial Proteins*
  • Blood Platelets / drug effects*
  • Blood Platelets / metabolism
  • Calcium / metabolism
  • Carrier Proteins / agonists
  • Cells, Cultured
  • DNA / biosynthesis
  • DNA / drug effects
  • Humans
  • Intracellular Signaling Peptides and Proteins*
  • Muscle, Smooth, Vascular / drug effects*
  • Muscle, Smooth, Vascular / metabolism
  • P-Selectin / biosynthesis
  • Peptide Fragments / metabolism
  • Platelet Aggregation / drug effects
  • Pyrroles / metabolism*
  • Pyrroles / pharmacology*
  • Quinazolines / metabolism*
  • Quinazolines / pharmacology*
  • RNA-Binding Proteins / antagonists & inhibitors
  • Receptor, PAR-1
  • Receptors, Thrombin / antagonists & inhibitors*
  • Receptors, Thrombin / metabolism
  • Thrombin / antagonists & inhibitors*
  • Thrombin / metabolism
  • Thymidine / metabolism
  • Transcription Factors / antagonists & inhibitors
  • Triallate


  • Apoptosis Regulatory Proteins
  • Bacterial Proteins
  • Carrier Proteins
  • Intracellular Signaling Peptides and Proteins
  • MtrB protein, Bacteria
  • N3-cyclopropyl-7-((4-(1-methylethyl)phenyl)methyl)-7H-pyrrolo(3, 2-f)quinazoline-1,3-diamine
  • P-Selectin
  • Peptide Fragments
  • Pyrroles
  • Quinazolines
  • RNA-Binding Proteins
  • Receptor, PAR-1
  • Receptors, Thrombin
  • Transcription Factors
  • prostate apoptosis response-4 protein
  • DNA
  • Triallate
  • Thrombin
  • Calcium
  • Thymidine