THE PLASMATIC COFACTOR OF THROMBOPLASTIN: ITS ADSORPTION, WITH PROTHROMBIN AND FIBRINOGEN, BY ALUMINA AND TRICALCIUM PHOSPHATE GELS

Abstract

The adsorption of prothrombin and fibrino-gen from the plasmas of man, dog and rabbit by aluminum hydroxide and by tricalcium phosphate was studied quantitatively. The latter reagent adsorbs prothrombin more efficiently and takes out relatively less fibrinogen. Less tricalcium phosphate is required to remove prothrombin from dog plasma immediately after recovery from dicumarol poisoning than from normal dog plasma. It was detd. by incubating thromboplastin with normal and stored plasma that no antithromboplastic agents are developed on aging. Likewise, no evidence of the formation of antithrombin occurs in 48 hrs., but may in older plasma. It is concluded that the agent which disappears on storage is a cofactor of thromboplastin. To establish whether a delay in prothrombin time is due to a lack of prothrombin or to a deficiency of the cofactor, the effect of the latter is tested on the plasma diluted 1/10 and 1/20. If it normalized the prothrombin time, the prolongation is due to a decrease of the cofactor.