SummaryThe role of Hageman factor in triggering intravascular coagulation has been studied in rabbits injected intravenously with Liquoid. Besides changes of coagulation parameters characteristic of consumption coagulopathy (e.g. decrease in platelet counts, fibrinogen levels, factor V activity), a pronounced drop in Hageman factor activity was observed after injection of Liquoid. Likewise, the partial thromboplastin time became prolonged.The activation of Hageman factor in vivo could be prevented by intravenous infusion of lysozyme. Twenty min after starting the lysozyme infusion, the partial thromboplastin time became prolonged from a mean of 29 sec to 108 sec. Animals infused with lysozyme and injected with a lethal dose of Liquoid did not develop a consumption coagulopathy. In the same manner, none of 10 animals treated with lysozyme developed the generalized Shwartzman reaction, whereas in the control group 19 out of 20 animals showed fibrin thrombi in the glomerular capillaries.From the present study it may be concluded that the intravascular coagulation process after intravenous injection of Liquoid is triggered by Hageman factor activation.

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SummaryThe protease inhibitor aprotinin reduced the incidence of the generalized Shwartzman reaction after Liquoid injection into the rabbit. This inhibitory effect is caused by the interference of aprotinin with the intravascular coagulation process (consumption coagulopathy) since decreases in fibrinogen levels after Liquoid injection were prevented. As the main anticoagulant effect of aprotinin is the inhibition of surface factor activation and as on the other hand Liquoid acts as a surface-active substance, it seems conceivable that aprotinin might prevent Liquoid-induced consumption coagulopathy by interfering with Hageman factor activation.Aprotinin did not have any effect on the incidence of hemorrhages in the lungs in Liquoid-injected animals.Furthermore, aprotinin prolonged the survival time of rabbits injected with Liquoid. This effect is not related to the action of aprotinin on the coagulation process.

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