The interactions of fibrinogen and dextrans with erythrocytes

Abstract

SUMMARY1. The rate of packing of erythrocytes in whole blood, under a centrifugal field of 200 9, has been studied using an automatic recording centrifuge.2. Reduction of the supernatant fibrinogen concentration, by repeatedly washing the cells, lowers the rate of packing and reduces the cell flexibility.3. Resuspending the cells in their own plasma or in isotonic solutions containing fibrinogen restores their flexibility.4. Rouleaux formation has been shown to have no effect on the rate of packing by comparison of blood diluted with plasma, isotonic NaCl or Ringer-Locke solutions. While the degree of rouleaux formation varied with the diluent used, the rate of packing and packed cell haematocrit were the same, for the same dilution.5. Both formalin and dextran altered the degree of rouleaux formation and reduced erythrocyte flexibility. Dextran was found to act indirectly on the erythrocyte flexibility by reducing the plasma fibrinogen concentration.

The Blood Rheology of Man and Various Animal Species

“…This critically depends on the erythrocyte flexibility, if this is low initially, as in sheep and cattle a decrease of flexibility increases blood viscosity at both high and low shear rates, because the contribution of aggregation to viscosity is small. In man, erythrocyte flexibility is related to the plasma fibrinogen level (Rampling & Sirs, 1972). No similar action was observed in sheep, cattle or horse, though it is known to affect rabbit cells.…”

“…The packing rates for rabbits, pigs, camels and dogs are comparable, though less than man; the erythrocytes of sheep, cattle and goats are less flexible, while those of horses are very flexible. Rampling & Sirs (1972) observed that the flexibility of human erythrocytes depends on the plasma fibrinogen concentration. This is also true of rabbit cells (Sirs & MacDonald, 1974).…”

The solubility of fibrinogen in solutions containing dextrans of various molecular weights (Short Communication)

“…The evidence concerning complex-formation is more equivocal (Bull et al, 1955). However, the fall in fibrinogen concentrations in subjects infused with dextran (Swank, 1958), the alteration in fibrin clot morphology in the presence of dextran (Muzaffar et al, 1972), and the effect of dextran on erythrocyte flexibility (Rampling & Sirs, 1972), all at concentrations below that that produces precipitation, are suggestive of complex-formation.…”

Plasma Exchange

“…At low shear rates a direct relationship between apparent blood viscosity and plasma fibrinogen concentration can be demonstrated, although this may not apply to very low fibrinogen levels (BHittler et al, 1979). The relationship between plasma fibrinogen concentration and red-cell deformability is not as yet settled (Rampling and Sirs, 1972;Dodds et al, 1979;Drummond et al, 1979).…”