Summary
We have investigated the antithrombotic properties of prothrombin fragment 1.2 (F1.2) in this study. To do this, we established the minimum concentration of human placental
tissue factor or human a-thrombin that was lethal in mice within 5 min after intravenous
injection. Prothrombin F1.2 protected the mice from the lethal effect of tissue factor or α-thrombin in a dose
dependent manner, with 500 μg (14 nmoles) of prothrombin F1.2 per mouse being the minimum amount required to protect all mice from the lethal effect
of either thrombogenic stimulus. The minimum dose of heparin which protected mice
from the lethal effect of thrombin or tissue factor was 6 units or ∼3.3 nmoles. The
observation that prothrombin F1.2 has antithrombotic properties suggests prothrombin F1.2 can modulate coagulation in vivo, as it has previously been shown to do in vitro.
