Effects of fibrinolytic agents and heparin on intravascular clot lysis

Abstract

Clots were prepared in glass or siliconized cannulae and inserted into jugular veins 5 cm distal to semiconstricting ligatures. Clots prepared in glass tubes propagated rapidly unless heparin was administered. Clots prepared on siliconized surfaces showed less tendency to grow. Heparin was the most effective agent in causing decrease in clot size (thrombolysis). The thrombolytic effects of the fibrinolytic agents were somewhat less than heparin and did not correlate well with their in vitro activities. Staphylokinase, dog fibrinolysin, and bromelain proved too toxic for adequate testings. Following Thrombolysin or Actase infusions the plasma fibrinolytic titers rose and the profibrinolytic and antifibrinolytic titers fell. Following streptokinase (SK) the plasma fibrinolytic titer rose but no changes in antifibrinolysin or profibrinolysin were observed. It was postulated that the apparent rise in fibrinolysin following SK may have been due to simultaneous adsorption of activator and profibrinolysin onto the substrate followed by in situ activation. Heparin caused no detectable changes in the dogs' fibrinolytic factors.