[Vitamin K-dependent inhibitor of thrombin formation]

Activity of thermostable inhibitor of thrombinoformation was decreased in blood serum after administration of pelenthane into animals. Simultaneous administration of vicasol limited this effect. Decrease in the activity of the inhibitor was also observed after partial hepatectomy and poisoning with CCl4. Correlation was not found between total coagulation activity, content of prothrombin and the inhibitor activity. The inhibitor was inactivated markedly in exogenous thromboplastinemia and lesser--in hyperheparinemia. The data obtained suggest that self regulation of blood coagulation system occurs at the level of synthesis of its biochemical components.