The role of Willebrand factor in platelet - blood vessel interaction, including a discussion of resistance to atherosclerosis in pigs with von Willebrand's disease.
Von Willebrand pigs have all the manifestations of the severe human disease. The role of Willebrand antigen (VIII R:AG) and ristocetin cofactor (VIII: RWF) was assessed in these pigs by (1) transfusion and (2) "in vitro" bleeding time assay. The skin bleeding time became normal when the level of transfused Willebrand factor (VIII R:AG/RWF) was raised in the plasma above 30 U/dl. After single or repeated transfusions, skin capillary endothelium and platelets were still distinguished from normal by VIII R:AG deficiency. When incisions in excised porcine skin ("in vitro" bleeding time) were perfused with blood and plasma fractions, haemostasis occurred when plasmatic Willebrand factor exceeded 30 U/dl whether the skin or platelets came from normal or from von Willebrand pigs. The platelet plug occluding the skin incision contained VIII R:AG by immunofluorescence. Willebrand factor appears to coat surfaces and to serve as a platelet attachment protein. These bleeder pigs are resistant to atherosclerosis. If platelets are involved in early atherosclerotic lesions, the role of Willebrand factor in platelet - blood vessel interaction may be important.
D000818:Animals; D001161:Arteriosclerosis / Q000209:etiology*; D001779:Blood Coagulation Factors / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology*; D004195:Disease Models, Animal; D004727:Endothelium / Q000502:physiology; D006487:Hemostasis; D010973:Platelet Adhesiveness; D012310:Ristocetin / Q000502:physiology; D013552:Swine; D014841:von Willebrand Factor / Q000502:physiology*
D001779:Blood Coagulation Factors; D014841:von Willebrand Factor; D012310:Ristocetin