ANTICOAGULANT EFFECT OF INCUBATED FIBRINOGEN

Abstract

Sterile fibrinogen rendered non-clottable by incubation was mixed with fresh plasma and the throm-bin time determined. An appreciable prolongation was observed. The incubated fibrinogen was then fractionally precipitated with ammonium sulphate. The material precipitated between 25 and 50% ammonium sulphate saturation, when added to freshly drawn but still unclotted blood, or native plasma, prevented its coagulation. This action could be reversed by an approximately fivefold dilution with distilled water and addition of calcium chloride and thrombin, thus excluding fibrinoly-sis as the cause of the anticoagulant effect. Determinations of the respective coagulation factors showed that no decrease occurred in prothrombin, factor VII, plasma thromboplastin component, and fibrino-gen. On the other hand a statistically significant decrease in factor V was observed when calcium was present.