SummaryA method was elaborated for determining e-aminocaproic acid (EACA) in blood plasma, based upon this compound’s antifibrinolytic activity.Oxalated plasma was deproteinized in a boiling water-bath using trichloracetic acid. The latter was removed from plasma filtrate by means of ether extraction and the effect of the deproteinized extract on clot fibrinolysis time under standard conditions was tested. There was found a linear correlation of the logarithm of clot lysis time with EACA concentration.The method appears to be fast and reliable, making possible serial determinations of the EACA level in blood plasma, the error being within the limits of 3 percent. It is suitable for the EACA level in plasma exceeding 2 mgVo.The method is most specific. Various amino acids appearing naturally (except cysteine) do not interfere with determinations.The EACA metabolism in vivo may be successfully studied using the above method.

SummaryEACA was administered orally to 30 healthy volunteers in a single doses of 0.1 g per kg body weight. The level of this compound in blood plasma and its effect on the human plasma fibrinolytic system were investigated.EACA is rapidly absorbed from the intestinal tract, its maximal level in the blood plasma being reached one hour later. The half life of this compound in the blood plasma amounted to two hours on the average.The following changes in the plasma fibrinolytic system were observed : a) an inhibition of euglobulin fibrinolysis, which was most pronounced three hours after EACA ingestion ; b) a considerable increase in plasminogen, antiplasmin and antitrypsin activities (maximum-five hours after EACA) ; c) slight increase in fibrinogen level (maximum-five hours after EACA).The conclusion has been reached that EACA induces a rise in endogenous inhibitors of the fibrinolytic system in the normal organism which may reinforce the hemostatic effect of this drug. The observed phenomena may be explained if we assume that the activation of the fibrinolytic system in the organism is continuous.

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SummaryTwo antiplasmins were found in human granulocytes. Chromatography on Sephadex G-200 showed 3 peaks with antiplasmin activity. One immediately acting antiplasmin and 2 progressively acting antiplasmin (I and II) have been identified. The immediate antiplasmin was purified 92-fold, the progressive antiplasmin 1129-fold and progressive antiplasmin II 185-fold. Disc electrophoresis showed homogeneity of the fractions. They were found to migrate with the alpha-2 globulin fraction. The physiological function of the antiplasmins is briefly discussed.