DETERMINATION OF THROMBIN AND PLASMIN ACTIVITY IN HUMAN BLOOD PLASMA USING THE TURBIDIMETRIC CURVE OF CLOT FORMATION AND DISSOLUTION

The aim of the study was to develop a method for determination the activity of thrombin, which is based on the turbidimetry curve of the formation and dissolution of a blood plasma clot. Methods. Donor blood samples were collected in 3.8% sodium citrate (1 part of sodium citrate and 9 parts of blood, pH 7.4). Plasma was separated from blood cells within 1 hour after blood collection by centrifugation the latter at 1200 g for 20 minutes. Aliquots of plasma were stored at -20 °C. Results. To determine the concentrations of thrombin and plasmin, TDCs of the formation and dissolution of blood plasma clots, initiated by the APTT reagent, were used. Based on the values of τ obtained, a calibration curve was constructed in the coordinates 1/τ – [Thr] (the rate of protofibrils formation in s-1 vs thrombin concentration in NIH units in 1 ml). Conclusion. The proposed methods to determine the activity of thrombin and plasmin made it possible to quantitatively calculate the rate of prothrombin activation in the lag period, the concentration and activity of thrombin based on the rate of fibrin and protofibrils formation as well as the activity and concentration of plasmin at the point of the complete clot dissolution,