STUDIES ON ACTIVATOR FORMATION IN HUMAN-PLASMA WITH STREPTOKINASE .3. INVESTIGATION OF ACTIVATOR KINETICS IN UNDILUTED PLASMA IN TERMS OF UROKINASE EQUIVALENTS

  • 1 January 1976
    • journal article
    • research article
    • Vol. 36  (3) , 566-581
Abstract
A new method is presented for estimating the activator (plasminogen-streptokinase complex) concentration in native plasma of patients undergoing streptokinase [SK] infusion. The principle of the method is based on clot lysis time as recorded by the thromboelastograph. The test clot constituents were bovine fibrinogen, bovine plasminogen, EDTA, human plasma (with unknown activator concentrations) and thrombin. In order to obtain a standardization line, urokinase dissolved in NaCl solution was substituted for patients'' plasma. Each lysis time can easily be converted into urokinase equivalent (CTA[Committee on Thrombolytic Agents]-u[units]/ml). SK and plasminogen molecules in undiluted patients'' plasma existed both in an activator-bound (equimolar plasminogen-SK complex) and in a freely circulating form. This result was in agreement with earlier findings where the activator complex was demonstrated to be a widely dissociated complex in highly diluted plasma of patients, displaying an ample proportion of free SK and plasminogen molecules. SK treatment using dosage schemes of 100,000 u SK/h, 150,000 u/h and 200,000 u/h were monitored by quantitative activator, SK and plasminogen measurements. An average activator concentration of 50-100 CTA-u/ml and a SK-concentration of 7-16 u/ml were recorded during SK infusion. Plasminogen values averaged 0.25%, independent of the amount of SK infused. Each drop in SK was accompanied by a drop in activator during the infusion, and each rise in SK by a rise in activator. There was a strong correlation between SK and activator concentrations in that, on the average, 1 u SK equalled 8.4 CTA-u/ml activator (correlation coefficient r = 0.9). The activator concentration in the plasma of patients undergoing fibrinolytic treatment can easily be adjusted by regulating the hourly SK influx.

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