Rheological characteristics of desialylated erythrocytes in relation to fibrinogen-induced aggregation

The effect of fibrinogen and sialic acid content of erythrocytes on the aggregation of erythrocytes was quantitatively examined by using a rheoscope combined with a television image analyzer and a computer. (1) The electrophoretic mobility of erythrocytes was proportional to the sialic acid content of erythrocytes (the surface potential of erythrocytes could be expressed by the sialic acid content). (2) The aggregation of erythrocytes was accelerated by increasing fibrinogen concentration in the medium (due to the increased bridging force among erythrocytes) or by decreasing the sialic acid content (due to the reduction of the electrostatic repulsive force among erythrocytes). (3) An empirical equation expressing the velocity of aggregate formation (ν, in μm²/min) by the concentration of fibrinogen ($\text{F}$, in g/dl) and the sialic acid content ($\text{S}$, in μmol/ml red blood cells), log $\text{ν = ?0.065 F}{}^{\mathrm{?1.2}}\text{S + 2.2 F}{}^{0.35}$, was deduced. (4) The contribution of the bridging force of fibrinogen to the erythrocyte aggregation was much greater than that of the electrostatic repulsive force produced by sialic acid on the surface of erythrocytes.