STUDIES ON THE INITIATION OF BLOOD COAGULATION. III. THE CLOTTING PROPERTIES OF CANINE PLATELET-FREE PLASMA 1

Abstract

It was possible to prepare platelet-free plasma without the use of anticoagulants by means of high-speed centrifugation at low temperature using silicone-treated apparatus. Such platelet-free plasma from normal dogs remained fluid when stored at body temp. in silicone-treated tubes but clotted on contact with glass. The rate of clotting was related to the glass area. When made platelet-free, blood from Irish Setters with a hereditary disease identical with human hemophilia did not clot even when in contact with crushed glass. The authors suggest that the clot-accelerating effect of glass surface is mediated by a "plasma thromboplastin." Hemophilic plasma is presumably deficient in plasma thromboplastin. It appears that either plasma thromboplastin or platelets alone can initiate coagulation, but both components are required for efficient'' clotting. The clot-accelerating effect of glass surfaces is mediated by the plasma factor rather than by any direct action on platelets.