title: Differential effect of a low-molecular-weight heparin (dalteparin) and unfractionated heparin on platelet interaction with the subendothelium under flow conditions.
abstract: Effects of heparins on platelet function are controversial, but perfusion studies, that simulate physiological conditions, might help to explain their clinical behaviour. We used a perfusion system to test the effect unfractionated heparin and a low-molecular-weight heparin (dalteparin, Fragmin) on platelet adhesion promoted by a damaged vascular surface. Normal blood samples containing increasing concentrations of unfractionated heparin and dalteparin were perfused through annular chambers containing enzymatically denuded rabbit aorta segments (5 min at 800 sec-1). Segments were evaluated morphometrically measuring the total surface covered by platelets and by large aggregates (thrombi). Unfractionated heparin inhibited platelet interaction with subendothelium in a lesser extent than dalteparin in both covered surface and thrombi (p < 0.01). At heparin doses that caused maximal inhibition covered surface was 10.0% +/- 3.1% with dalteparin and 18.3% +/- 4.2% with unfractionated heparin, and thrombi were 5.6% +/- 3.2% and 12.3% +/- 3.0%, respectively. These results may collaborate to explain some differences observed in the clinical results obtained with unfractionated heparin and with dalteparin.
authors.affiliation: Department of Hemotherapy and Hemostasis, Hospital Clinic, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Serra
authors.forename: J
authors.initials: J
authors.lastname: Esteve
authors.forename: J C
authors.initials: JC
authors.lastname: Reverter
authors.forename: M
authors.initials: M
authors.lastname: Lozano
authors.forename: G
authors.initials: G
authors.lastname: Escolar
authors.forename: A
authors.initials: A
authors.lastname: Ordinas
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000166:cytology* / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D002450:Cell Communication / Q000187:drug effects*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006493:Heparin / Q000494:pharmacology*; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology*; D006801:Humans; D011817:Rabbits
chemical_list: D005343:Fibrinolytic Agents; D006495:Heparin, Low-Molecular-Weight; D006493:Heparin