title: Collagen-induced generation of platelet-derived microparticles in whole blood is dependent on ADP released from red blood cells and calcium ions.
abstract: We have evaluated the effects of different anti-coagulants or agonists on the generation of platelet-derived microparticles (PMPs) using flow cytometry. Twenty microg/ml of collagen induced significantly greater PMP formation in whole blood anti-coagulated with argatroban, a selective thrombin inhibitor, as compared with platelet-rich plasma, or whole blood anti-coagulated with citrate. Thus, whole blood kept at the physiological Ca2+ concentration provides an optimal condition for the formation of PMP. Convulxin, a GPVI-selective agonist, also induced PMP formation at the magnitude which far exceeds those of other agonists, such as thrombin receptor-activating peptide, ADP or epinephrine. These findings suggest that GPVI-mediated platelet activation plays a key role in the formation of PMP in the presence of physiological Ca2+ in whole blood. The addition of red blood cells to PRP potentiated PMP formation induced by collagen. Pretreatment of whole blood with the combination of creatine phosphate and creatine phosphokinase reduced PMP formation induced by collagen. Blockade of ADP receptors, P2Y12 with AR-C69931MX and P2Y1 with A3P5P, respectively, further suppressed collagen-induced PMP formation. We conclude that ADP released from red blood cells enhances PMP formation induced by collagen, and that both P2Y12 and P2Y1 contribute to ADP-potentiation of PMP generation induced by collagen.
authors.affiliation: Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Tamaho, Nakakoma, 409-3898, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Takano
authors.forename: Naoki
authors.initials: N
authors.lastname: Asazuma
authors.forename: Kaneo
authors.initials: K
authors.lastname: Satoh
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yatomi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ozaki
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000502:physiology; D001120:Arginine / Q000031:analogs & derivatives; D001792:Blood Platelets / Q000648:ultrastructure*; D002118:Calcium / Q000378:metabolism; D003094:Collagen / Q000494:pharmacology*; D003435:Crotalid Venoms / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D037181:Lectins, C-Type; D008565:Membrane Proteins / Q000502:physiology*; D010316:Particle Size; D010875:Pipecolic Acids / Q000494:pharmacology; D015539:Platelet Activation / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D013449:Sulfonamides
chemical_list: D003435:Crotalid Venoms; D037181:Lectins, C-Type; D008565:Membrane Proteins; C546382:P2RY1 protein, human; C548576:P2RY12 protein, human; D010875:Pipecolic Acids; D010980:Platelet Membrane Glycoproteins; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058925:Receptors, Purinergic P2Y12; D013449:Sulfonamides; C098341:platelet membrane glycoprotein VI; C028890:convulxin; D000244:Adenosine Diphosphate; D003094:Collagen; D001120:Arginine; C031942:argatroban; D002118:Calcium