Dose-dependent effect on thrombus weight in the guinea pig AV shunt thrombosis model. PC variants were infused for 15 minutes before and throughout a 15-minute period of blood circulation through the shunt. Thrombi were removed and weighed after 30 minutes of infusion. The numbers in parentheses represent the calculated infusion dose (mg/kg/h) required to reduce thrombus weight to 20 mg under the conditions of the experiment. The number of animals per dose ranged from 4 to 11 for aPC and from 2 to 4 for the zymogens.