In vivo activation of the fibrinolytic enzyme system of dogs

¹ Cardiovascular Research Institute, University of California School of Medicine, San Francisco, California

We studied the effect of streptokinase and small amounts of human plasmin on the components of the fibrinolytic enzyme system of the dog. A 1-hr infusion of streptokinase (500 U/ml blood volume) and plasmin (.001 mg/ml blood volume) in dogs produced during the infusion: 1) No adverse immune reaction. 2) Enhanced lysis of blood clots. 3) Decreased serum plasminogen and plasma plasmin inhibitor levels. 4) Decreased plasma fibrinogen levels. The clot lysis rates, plasminogen, and plasma plasmin inhibitor levels returned to one-half their preinfusion level within 4–8 hr. The fibrinogen level returned to one-half its preinfusion level after 12 hr.