Inhibition of Thromboplastin‐Induced Intravascular Coagulation by Heparin and Trasylol

Homologous brain thromboplastin was injected or infused in different ways in dogs, and various coagulation factors were followed for 7 days. Slow infusions of thromboplastin in anesthetized dogs caused changes in platelet count and fibrinogen concentration similar to those usually seen in the postoperative period in man. The heparin co‐factor decreased only slightly, which is contrary to the postoperative reactions in both man and dogs. The decrease in platelet count and fibrinogen concentration and the rate of thromboemboli after intravenous thromboplastin administration could partly be inhibited, if the dogs were treated prophylactically with Trasylol, and completely inhibited, if they were pretreated with heparin. Trasylol also seemed to exert some slight influence on the antithrombin level in the circulating blood. The in vivo anticoagulant effect of Trasylol might be the result of partial inhibition of more than one reaction in the coagulation process. Compared to heparin Trasylol is a weak anticoagulant.