Changes in fibrinogen level after infusion of thrombin and thromboplastin

Abstract

Dogs, rabbits and rats were infused with dilute solutions of thrombin or thromboplastin. Changes in fibrinogen levels were estimated by two methods. One method measured precipitable fibrinogen and the other measured changes in coagulability. In rabbits an infusion rate of 2–3 u of topical thrombin per minute was well tolerated. Significant decreases in fibrinogen were observed with as little as 100 u of thrombin. In dogs 5 u/min. was tolerated and 200 u were required to show significant change in fibrinogen level. Complete defibrination was achieved in both species with larger total doses. Rats were refractory to topical thrombin administered in this way. They tolerated a rate of infusion equal to that of the rabbit and showed only slight changes in fibrinogen with 100 u of thrombin. Thromboplastin was often more effective in decreasing fibrinogen levels in the rat but was quite variable in its action. In all three species the fibrinogen level was significantly elevated 24 hours after an infusion. Saline was as effective as thrombin or thromboplastin in this regard.