Activation of Thromboplastinogen by Thrombin

Abstract

Human blood collected and clotted in a silicone-coated tube has a serum prothrombin time almost identical with that of the plasma prior to coagulation. The clotting of plasma by platelet extract results in little consumption of prothrombin if non-wettable surfaces are used. if thrombin and platelet extract are added to plasma, good prothrombin consumption will result even in a silicone-coated tube. This indicates that the plasma factor, thromboplastinogen, does not react with the platelet agent until it has been activated by thrombin. The adsorption of thrombin to glass probably explains the accelerating influence of this surface on clotting. The similarity of platelet extract and thromboplastin heated to 60[degree] is discussed.