Fundamental Interactions and Effect of Storage, Ether, Adsorbants and Blood Clotting on Plasma Antithrombin Activity

Abstract

Neither the quantity of thrombin neutralized by antithrombin nor the rate of its neutralization is changed by the addition of heparin. The quantity of thrombin which antithrombin can neutralize is a function of the initial concn. of the purified thrombin substrate itself. This function has been detd. in detail. In dilute solns., the interaction of thrombin and antithrombin is slower than in concd. soln. An increase in temp. increases the rate of interaction. Under ordinary refrigerator storage conditions, antithrombin is stable for at least 4 weeks in human plasma, cow plasma, human blood, cow blood, human serum and cow serum. After 13 weeks, most of the antithrombin activity is gone. The concn. of anti-thrombin in human serum is lower than in the plasma, indicating that most of the thrombin derived from prothrombin during the clotting process is neutralized by antithrombin and by the mechanisms studied. Extraction of serum or plasma with ether destroys the antithrombin activity. The activity is not adsorbed on a variety of common adsorbants such as kaolin, tricalcium sulphate, Fuller''s earth, magnesium oxide, activated charcoal, asbestos, Lloyd''s reagent or barium sulphate. A method has been devised and descr. for the quantitative detn. of plasma antithrombin activity.