Serum and Plasma Antithrombin.

Abstract

A method of estimating the rate of natural antithrombic activity is suggested. When this method was used, dog plasma, regardless of the prothrombin level after dicumarolization, seemed to exert about the same antithrombic activity. On the other hand, dog serum antithrom-bin varied inversely with the prothrombin content of its original plasma, and serum obtained from blood containing little prothrombin was antithrombic to about the same extent as plasma. These observations suggest that antithrombic activity be detd. on plasma unless due consideration is given to the antithrombic activity already performed by serum.