On the mechanism of plasmin-induced platelet aggregation. Implications of the dual role of granule ADP.
Plasmin-induced platelet aggregation has been considered to be a cause of reocclusion after thrombolytic treatment with plasminogen activators. However, little is known regarding the mechanism and regulation of plasmin-induced platelet aggregation. In this study, we demonstrated that plasmin causes the degranulation of platelets, and that ADP released from granules plays a crucial role in the induction of platelet aggregation. This conclusion is supported by results showing that both ADP antagonists and ADPase can inhibit the effect of plasmin on platelets. We also demonstrated that pretreatment of platelets with ADP makes the platelets more sensitive to plasmin, and plasmin-induced platelet aggregation is, therefore, observed at lower concentrations where no aggregation occurs in quiescent platelets. In other words, it is thought that ADP potentiates the plasmin-induced aggregation. The effect of ADP was inhibited by N(6)-[2-(methylthio)-ethyl]-2-(3,3, 3-trifluoropropyl)thio-5'-adenylic acid, monoanhydride with dichloromethylenebisphosphonic acid (AR-C69931), a selective antagonist for the P2T(AC) subtype of P2 receptor, but not by the P2Y1 receptor-selective antagonist adenosine 3'-phosphate 5'-phosphosulfate (A3P5PS). The P2X1 receptor agonist alpha, beta-methylene adenosine 5'-triphosphate (alpha,beta-MeATP) did not mimic the action of ADP. These data indicate that ADP potentiates plasmin-induced platelet aggregation via the P2T(AC) receptor. In addition, epinephrine, a typical G(i) agonist against platelets, could potentiate the plasmin-induced platelet aggregation, suggesting that the signal via the G(i) protein is involved in potentiating the plasmin-induced platelet aggregation, ADP is secreted from platelet granules, and concomitantly works in conjunction with plasmin in a P2T(AC) receptor-mediated manner.
Ishii-Watabe
A
A
Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, Tokyo, Japan. watabe@nihs.go.jp
Uchida
E
E
Mizuguchi
H
H
Hayakawa
T
T
D000244:Adenosine Diphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D001081:Apyrase / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000187:drug effects; D004347:Drug Interactions; D004837:Epinephrine / Q000494:pharmacology; D005341:Fibrinolysin / Q000494:pharmacology*; D005343:Fibrinolytic Agents / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008024:Ligands; D008565:Membrane Proteins; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058925:Receptors, Purinergic P2Y12
D000067956:Adenylyl Cyclase Inhibitors; D005343:Fibrinolytic Agents; D008024:Ligands; D008565:Membrane Proteins; C548576:P2RY12 protein, human; D010975:Platelet Aggregation Inhibitors; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; C117446:cangrelor; D005341:Fibrinolysin; D001081:Apyrase; D002118:Calcium; D004837:Epinephrine