Kinins and thrombolysis.

In cats with extracorporeal circulation arterial blood pressure and thrombolysis were assayed. In this model apart from their hypotensive properties kallikrein (3-10 units/kg, i.v.) and captopril (> 200 micrograms/kg, i.v.) dissipated blood clots which were preformed on superfused collagen strips. Captopril at a lower dose of 50 micrograms/kg i.v. potentiated the thrombolytic effect of kallikrein while aprotinin (100,000 unit/kg, i.v.) abolished it. Thrombolysis by kallikrein was mediated by an unstable principle which was decomposed by blood during 15 min of incubation at 37 degrees C. Generation of this principle was inhibited by pretreatment of animals with aspirin (50 mg/kg, i.v.). The above analysis points to prostacyclin which owing to its platelet-suppressant and fibrinolytic properties induces thrombolysis when released by kinins.