title: Effects of inhibition of P2Y(1) and P2Y(12) on whole blood clotting, coagulum elasticity and fibrinolysis resistance studied with free oscillation rheometry.
abstract: BACKGROUND
  In vivo, initial platelet activation is likely caused by platelet contacts with collagen in the subendothelium or from the small amounts of thrombin formed by the tissue factor/factor VIIa complex. Our aim was to study the coagulative role of ADP released by the platelets after activation with strong stimuli such as collagen and/or thrombin, and the relative importance of the platelet ADP receptors P2Y(1) and P2Y(12).
  
  
  METHODS
  We used 10 Hz free oscillation rheometry to measure clotting time, clot elasticity and fibrinolysis resistance of non-anticoagulated whole blood. The platelets were activated with a collagen-related peptide (CRP), with the PAR1 thrombin receptor activating peptide TRAP-6 or by thrombin, the latter generated by small amounts of thromboplastin. To inhibit the platelet ADP receptors, we used the P2Y(1) antagonist MRS2179 and the P2Y(12) antagonist AR-C69931MX.
  
  
  RESULTS
  Both antagonists significantly retarded the clotting induced by CRP. The effects were most pronounced with AR-C69931MX. For TRAP-6, the same trend was seen, but the retardation was only significant with AR-C69931MX. Clotting induced by small amounts of thromboplastin was not affected by any ADP-receptor antagonist. Addition of both antagonists did not change the results as compared to samples with AR-C69931MX alone. Nor did the antagonists, one at a time or in concert, effect fibrinolysis or the elastic properties of the clot.
  
  
  CONCLUSIONS
  We conclude that ADP-receptor inhibition prolongs the clotting time for whole blood activated by CRP, but that it does not affect the properties of the subsequently formed coagulum.
authors.affiliation: Department of Biomedicine and Surgery, Division of Clinical Chemistry, University Hospital, SE-581 85, Linköping, Sweden. sofra@ifm.liu.se
authors.forename: Sofia
authors.initials: S
authors.lastname: Ramström
authors.forename: Mats
authors.initials: M
authors.lastname: Rånby
authors.forename: Tomas L
authors.initials: TL
authors.lastname: Lindahl
mesh_terms: D000244:Adenosine Diphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000328:Adult; D001777:Blood Coagulation / Q000187:drug effects*; D002352:Carrier Proteins / Q000494:pharmacology; D004548:Elasticity; D005342:Fibrinolysis / Q000187:drug effects; D005434:Flow Cytometry; D018056:Hemorheology; D006629:Hirudins / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000502:physiology; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D011994:Recombinant Proteins / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000494:pharmacology; D014914:Whole Blood Coagulation Time
chemical_list: D002352:Carrier Proteins; D006629:Hirudins; D008565:Membrane Proteins; C111914:N(6)-methyl-2'-deoxyadenosine 3',5'-diphosphate; C546382:P2RY1 protein, human; C548576:P2RY12 protein, human; D010446:Peptide Fragments; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D011994:Recombinant Proteins; C435908:collagen-related peptide; C082835:thrombin receptor peptide (42-47); D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; C117446:cangrelor; D010959:Tissue Plasminogen Activator; C083544:lepirudin