Platelet adhesion to glass has been directly determined with a cover slip chamber. These studies have separated the functions of platelet adhesion to a foreign surface from platelet cohesion (aggregation). The forces of the platelet-glass interaction have been studied, and the qualitative variables affecting this interaction have been defined. Fibrinogen and calcium or magnesium are required fo...

We describe glycoprotein (GP) Ib as a mediator of adhesion to fibronectin, specifically in flow. A monoclonal antibody (MoAb) directed to the von Willebrand factor (vWF)-binding site on this receptor or the absence of this receptor on the platelet membrane, in the case of a patient with the Bernard-Soulier syndrome, reduced platelet coverage to fibronectin to approximately 30% of the control va...

Previous studies have indicated that activated blood platelets interact with fibronectin through binding of fibronectin to the glycoprotein llb-Illa complex (GPIIb-llla). The cell attachment site of fibronectin with its crucial arg-glyasp(-ser) [RGD(S)]sequence is involved in these bindings. We studied the importance of these interactions for the fibronectin dependence of platelet adhesion unde...

Background. Nitric oxide (NO) has been identified as endothelium-derived relaxing factor (EDRF), which, in addition to its relaxant effects on vascular smooth muscle cells, is also a potent inhibitor of platelet aggregation. An inhibitory role on platelet adhesion has been suggested from experiments with washed platelets under static conditions. We have determined whether endothelium-derived an...

Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPa...

Adhesion of platelets to the damaged subendothelium is a prerequisite reaction for the initiation of hemostasis in vivo. Platelet membranes contain high concentrations of integrins and other glycoproteins (GPs) that are involved in the platelet adhesion to the extracellular matrix. In the present review, we focus on two platelet integrins, integrin alphaIIb beta3 (GPIIb/IIIa) and integrin alpha...

Divalent cation-dependent platelet adhesion to fibronectin (FN) is mediated by the integrin receptors alpha 5 beta 1 (GP Ic-IIa) and alpha IIb beta 3 (GP IIb-IIIa), which recognize the RGD (Arg-Gly-Asp) sequence in the cell-binding domain. However, FN can also support divalent cation-independent platelet adhesion. To determine which domain of FN mediates divalent cation-independent adhesion, pr...

To assess the relative importance of the glycoprotein (GP) Ib binding domain and the RGDS binding site in platelet adhesion to isolated von Willebrand factor (vWF) and to collagen preincubated with vWF, we deleted the A1 domain yielding delta A1-vWF and introduced an aspartate-to-glycine substitution in the RGDS sequence by site-directed mutagenesis (RGGS-vWF). Recombinant delta A1-vWF and RGGS...

Three glycoproteins (GPs), namely GPIa-IIa, GPVI, and GPIV, have been recently implicated in platelet-collagen adhesive interactions. We have employed antibodies to these GPs to investigate further their role in platelet adhesion to immobilized monomeric and polymeric fibrillar collagen under static conditions in the presence and the absence of Mg2+. In the presence of Mg2+, each antibody inhib...