Adherent platelets were examined for their ability to form microvesicles and procoagulant sites for thrombin formation. Epifluorescence and phase-contrast microscopy were employed to visualize shape changes, changes in intracellular Ca(2+) levels ([Ca(2+)](i)), vesiculation of the plasma membrane and appearance of anionic phospholipids in the outer leaflet of the plasma membrane, as probed by a...

Platelets will normally adhere to ‘damaged’ vessel walls and to other ‘activated’ platelets in flowing blood (1); platelets adhere from flowing whole blood onto vessel segments (2) and onto solid surfaces in flow chambers coated with extracellular matrix or purified adhesive proteins ( 3-5). Neutrophils can adhere to each other and to platelets in flowing suspension (6) or adhere to platelets i...

The adherence to collagen of rabbit platelets labeled in vivo with (35)SO(4) (=) has been studied both in vitro and in vivo. The young platelets are labeled with (35)SO(4) (=) 2-3 days after administration of the isotope to the animals. We exposed platelet-rich plasma (ethylenediamine-tetraacetate, EDTA, as anticoagulant), prepared from blood taken from rabbits 54 hr after giving the (35)SO(4) ...

BACKGROUND It is well known that platelets have a thrombotic effect. However, platelets play an important role not only in hemostasis but also in wound healing and tissue regeneration. Platelets have been reported to accumulate in the liver and promote liver regeneration after an extended hepatectomy, but the mechanism is unclear. The present study was designed to clarify the mechanism by which...

Platelets contain a pool of endogenous platelet-von Willebrand factor (vWF) that becomes expressed on the platelet surface when platelets are stimulated by a variety of agonists. Maximal platelet-vWF expression occurs in concert with platelet alpha-granule secretion. Aspirin (ASA) is known to impair platelet activation and alpha-granule secretion by irreversible inhibition of platelet cyclo-oxy...

Blood platelets have essential roles in hemostasis and thrombosis, inflammation, host defense, and wound healing. Emerging evidence from recent in vitro and in vivo studies suggests that platelets have a pivotal role in liver regeneration. In experimental animal models in which platelets were depleted or functionally impaired, liver regeneration after a partial liver resection was substantially...

The adapter protein SLP-76 is a critical mediator of signal transduction via the platelet collagen receptor glycoprotein VI (GPVI) and its coreceptor FcRgamma. We tested the hypothesis that SLP-76 is required for collagen-induced procoagulant responses in murine platelets. Platelets from SLP-76 null (SLP-76(-/-)) or heterozygous (SLP-76(+/-)) mice were activated with the GPVI agonist convulxin,...

Fibrinogen enhances the adenosine diphosphate (ADP) induced aggregation of washed rabbit platelets and has previously been shown to associate with platelets upon the addition of ADP. This association has been investigated further by measuring the binding of 125I-fibrinogen to platelets exposed to ADP under physiologic conditions of aggregation and deaggregation. To determine the extent of 125I-...

An expanding body of evidence continues to build on the role of platelets as initial actors in the development of atherosclerotic lesions. Platelets bind to leukocytes and endothelial cells, and initiate monocyte transformation into macrophages. Platelets internalize oxidized phospholipids and promote foam cell formation. Platelets also recruit progenitor cells to the scene that are able to dif...

Essentials Platelets play an important role in pathogen recognition. Platelets contain several complement factors and can interact with E. coli. Platelet's complement protein C3 differs from plasmatic C3 in its electrophoretic mobility. Upon contact with bacteria, platelets are activated and can enhance complement activation. SUMMARY Background The role of platelets in immune defense is incre...