ИСТИНА

Fibrinogen-induced RBC aggregation (RBC-A) has been considered to be caused by fibrinogen nonspecific binding to membranes and further leading to molecular bridging between interacting cells. In contrast, platelets are known to have a membrane integrin IIb/IIIa glycoproteins highly specific to fibrinogen. In this report we present the results of microrheologic study using aggregometer RheoScan AnD-300 of the effect of integrin IIb/IIIa glycoproteins inhibition on fibrinogen adsorption on RBC membrane by measuring the hydrodynamic strength of RBC aggregates in the flow of blood suspension in the microchannel in terms of critical shear stress (CSS). CSS equals the minimal shear stress required to disperse RBCs aggregates in blood sample flow. We studied the effect of several commonly used glycoprotein IIb/IIIa inhibitors: RGDS, eptifibatide, tirofiban. After incubating RBC in buffer solution, containing fibrinogen (at 3 mg/ml) and any of these inhibitors, after resuspension in platelet poor plasma at 40% HCT, the CSS significantly decreased: -23% ([RGDS] 2.6 mg/ml); -24% ([eptifibatide] 3.3 mkg/ml); -30% ([tirofiban] 4.8 mkg/ml) vs. control (220±55 mPa). Similar results were obtained after resuspension in serum. All experiments were performed on the blood of 1 healthy male donor using EDTA as anti-coagulant. The whole number of measurements for each inhibitor concentration was not less than 25. We conclude that there is an inhibition effect which may serve as an evidence of the existence of fibrinogen specific binding sites with IIb/IIIa glycoprotein related structure on RBC membrane. The observed effect of CSS decrease was not strongly dose-dependent which points on more complicated molecular structure. The study was supported by RFBR grants #17-02-01200 and #18-32-00756.