Quantitation of microparticles released from coated-platelets.
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.
Dale
G L
GL
Department of Medicine, W.K. Warren Medical Research Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA. george-dale@ouhsc.edu
Remenyi
G
G
Friese
P
P
D015703:Antigens, CD / Q000032:analysis; D001792:Blood Platelets / Q000737:chemistry / Q000648:ultrastructure*; D003435:Crotalid Venoms / Q000494:pharmacology; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D019276:Glycocalyx / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins / Q000032:analysis; D008722:Methods; D008856:Microscopy, Fluorescence; D010316:Particle Size; D010718:Phosphatidylserines / Q000032:analysis; D015539:Platelet Activation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000032:analysis; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis; D060245:Tetraspanin 29; D013917:Thrombin / Q000494:pharmacology
D015703:Antigens, CD; C554869:CD9 protein, human; D003435:Crotalid Venoms; D005456:Fluorescent Dyes; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D010718:Phosphatidylserines; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019038:Platelet Glycoprotein GPIb-IX Complex; D060245:Tetraspanin 29; C028890:convulxin; D013917:Thrombin