title: Assessment of platelet function in horses: ultrastructure, flow cytometry, and perfusion techniques.
abstract: We studied equine platelet function and activation using ultrastructural examination, flow cytometry, and perfusion. The main aim of the study was to evaluate hemostatic mechanisms in horses using these techniques. Ultrastructural observations were done on resting and activated platelets. Flow cytometry was used to evaluate binding of antibodies to major platelet glycoproteins (GPIIb-IIIa, GPIV, and GPIb) and activation-dependent antigens (P-selectin and lysosomal integral membrane protein [LIMP]). Perfusion techniques were used to evaluate the interaction between platelets and damaged subendothelium. Aggregation experiments were done to identify the best agonists for flow cytometry. Ultrastructural observations confirmed that equine platelets lack a developed open canalicular system and that release of granule contents occurs by fusion of adjacent granule membranes that ultimately connect with external membranes. Flow cytometry identified a 2-fold increase in binding of antibodies against GPIIb-IIIa and GPIV after activation. Binding of antibodies against P-selectin and LIMP increased from 2.12 and 1.74% to 15.5 and 11.6%, respectively, in response to thrombin and to 21.86 and 10.50%, respectively, in response to collagen. Annexin V binding increased moderately after activation. Perfusion experiments with citrated blood indicated that equine platelets react more strongly to subendothelium than do human platelets. When blood was anticoagulated with low molecular weight heparin, a marked impairment of platelet interactions was observed. In conclusion, although some differences were observed between human and equine platelet function, some techniques currently used to assess human platelet function may be useful to assess equine platelets.
authors.affiliation: Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: Dídac
authors.initials: D
authors.lastname: Segura
authors.forename: Luis
authors.initials: L
authors.lastname: Monreal
authors.forename: Sílvia
authors.initials: S
authors.lastname: Pérez-Pujol
authors.forename: Marcos
authors.initials: M
authors.lastname: Pino
authors.forename: Antonio
authors.initials: A
authors.lastname: Ordinas
authors.forename: Rosa
authors.initials: R
authors.lastname: Brugués
authors.forename: James G
authors.initials: JG
authors.lastname: White
authors.forename: Ginés
authors.initials: G
authors.lastname: Escolar
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D005434:Flow Cytometry / Q000662:veterinary; D006489:Hemostatic Techniques / Q000662:veterinary; D006736:Horses / Q000097:blood*; D006801:Humans; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D010477:Perfusion / Q000662:veterinary; D010974:Platelet Aggregation / Q000502:physiology*; D010980:Platelet Membrane Glycoproteins / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D010980:Platelet Membrane Glycoproteins