Studies on the influence of heparin on trypsin-induced shock in dog.

Intravenous infusion of bovine trypsin in dogs can induce intravascular coagulation, which is claimed to be one of the causes of the shock accompanying such infusions. Treatment with heparin prior to trypsin administration prevents the usual decrease of fibrinogen but apparently does not influence the trypsin-induced shock seen upon trypsin saturation of alpha 2-macroglobulin. The prompt appearance of fibrinogen fragments following trypsin saturation of alpha 2-macroglobulin is probably a consequence of plasminogen activation. Under similar conditions alpha 1-antitrypsin (alpha 1-protease inhibitor) seems to be acting as plasma inhibitor in the absence of free alpha 2-macroglobulin and the fast reacting plasmin inhibitor, antiplasmin. Thus, trypsin-induced shock in dogs is apparently not caused by intravascular coagulation to any significant degree.