Alterations of Plasmin Activity, Plasminogen Levels and Activity of Anti-Plasmins During Endotoxin Shock in Dogs

Endotoxin shock was induced in dogs by intravenous infusion of a lethal dose of E. coli endotoxin over a period of 3 hours. Typical changes of cardiovascular parameters were found and evidence of an intravascular clotting process was observed. Spontaneous plasmin activity and “immediate” and “time dependent” antiplasmin activities were determined by means of assays utilizing the chromogenic tripeptide derivative S-2251(Kabi Peptide Research Division, Mölndal, Sweden). Levels of plasminogen, α₂-macrolobulin (α₂-M) , and ai-antitrypsin(α₁-AT) were determined immunochemically. During shock, gradually decreasing values of “immediate” antiplasmin and α₂M were observed. During the late stages of shock “immediate” antiplasmin was found to be reduced by up to 89 per cent and α₂M up to 50 per cent of pre endotoxin infusion values. A less marked lowering of “time dependent” antiplasmin and α₁-AT also occurred during shock. These changes of plasma antiplasmins were accompanied by decreasing values of plasminogen and evidence of plasmin activity. These findings indicate that plasminogen is converted to plasmin during endotoxin shock and emphasize the role of antiplasmins in the pathophysiology of endotoxin shock.