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pubmed:abstractText |
Dual agonist stimulation of platelets with thrombin and convulxin results in generation of coated-platelets, a sub-population of cells known formerly as COAT-platelets (collagen and thrombin). Coated-platelets retain several procoagulant proteins on their surface and express phosphatidylserine (PS). In this report, we utilize a new methodology to demonstrate that coated-platelets also release microparticles. Platelets were prelabeled with 2.5 microm Bodipy-maleimide and then stimulated with convulxin plus thrombin. Microparticles, 0.3-0.5 microm in diameter, were observed by fluorescence confocal microscopy. Confocal microscopy was also used to demonstrate that microparticles were positive for glycoprotein IIb/IIIa, glycoprotein Ib, CD9, and PS, but negative for fibrinogen and thrombospondin. Furthermore, microparticles released from Bodipy-labeled platelets were observed by flow cytometry, and activation with convulxin plus thrombin produced 15 +/- 5 microparticles per coated-platelet. In contrast, platelets stimulated with thrombin or convulxin alone produced few microparticles. Phenylarsine oxide and diamide, both of which potentiate the mitochondrial permeability transition pore and coated-platelet production, significantly increased the number of microparticles released per coated-platelet.
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pubmed:affiliation |
Department of Medicine, W.K. Warren Medical Research Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA. george-dale@ouhsc.edu
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, N.I.H., Extramural
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