title: Energy-dependent expression of platelet-von Willebrand factor on the surface of unstimulated and stimulated platelets.
abstract: We have studied the energy requirements (adenosine triphosphate) for the expression of platelet-von Willbrand factor on platelets under conditions in which glycolysis and/or oxidative phosphorylation were inhibited. We found that platelet-vWf expression on the surfaces of both unstimulated and stimulated platelets required energy and was maximally decreased when metabolic ATP was maximally depleted. Platelet-vWf expression correlated directly with estimates of adenylate energy charge in both unstimulated and stimulated platelets. In addition, platelet shape change and agonist-induced intracellular Ca2+ flux were maintained at lower AECs than were either platelet aggregation or alpha-granule secretion. Our results indicate that the surface expression of platelet-vWf on unstimulated platelets is a dynamic process, and that energy is required to maintain basal amounts of platelet-vWf on the platelet surface. Our data also suggest that the metabolic ATP required to effect changes in platelet shape is less than that necessary to maintain basal platelet-vWf surface expression or to produce full alpha-granule secretion. We show that platelet-shape change in the absence of alpha-granule secretion can result in an increase in platelet-vWf surface expression.
authors.affiliation: Clinical Pathology Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: R I
authors.initials: RI
authors.lastname: Parker
authors.forename: H R
authors.initials: HR
authors.lastname: Gralnick
mesh_terms: D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D002462:Cell Membrane / Q000378:metabolism; D048429:Cell Size; D003847:Deoxyglucose / Q000494:pharmacology; D004734:Energy Metabolism; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D010085:Oxidative Phosphorylation / Q000187:drug effects; D015539:Platelet Activation; D010974:Platelet Aggregation; D011190:Potassium Cyanide / Q000494:pharmacology; D011485:Protein Binding; D012402:Rotenone / Q000494:pharmacology; D013917:Thrombin / Q000378:metabolism / Q000494:pharmacology; D001620:beta-Thromboglobulin / Q000378:metabolism; D014841:von Willebrand Factor / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D001620:beta-Thromboglobulin; D014841:von Willebrand Factor; D012402:Rotenone; C032456:antimycin; D000968:Antimycin A; D000255:Adenosine Triphosphate; D003847:Deoxyglucose; D013917:Thrombin; D011190:Potassium Cyanide; D019297:2,4-Dinitrophenol; D002118:Calcium