Plasma albumin is essential for collagen-induced platelet aggregation.
We found that platelets must have albumin on the surface to respond to collagen and aggregate. Albumin, however, was not absolutely necessary for ADP-, platelet activating factor-, serotonin- or thrombin-induced aggregation, while fibrinogen was required for ADP- or serotonin-induced aggregation. Immunofluorescent microscopy revealed that albumin was retained on gel-filtrated platelets but not on washed platelets. Albumin was not required for platelet adhesion to immobilized collagen. Without albumin thromboxane formation upon collagen-stimulation was diminished. These data suggest that albumin is essential in some step(s) that results in production of thromboxane A2.
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002462:Cell Membrane / Q000502:physiology; D003094:Collagen / Q000378:metabolism / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects*; D012709:Serum Albumin / Q000032:analysis / Q000502:physiology*; D013931:Thromboxanes / Q000096:biosynthesis
D012709:Serum Albumin; D013931:Thromboxanes; D003094:Collagen