Contribution of the platelet factor V content to platelet factor 3 activity.

The procoagulant activity obtained from bovine thrombocytes has been compared to that of lipids isolated from platelets, with and without the addition of purified bovine factor V. A one-stage assay, which consisted of delipidated bovine plasma containing RVV-activated factor X, was used to assess the activity. At low lipid concentrations no difference in coagulant activity was found between sonicated vesicles of extracted platelet lipid and lysed platelets.