AJP - Heart and Circulatory Physiology, Vol 236, Issue 3 447-H450, Copyright © 1979 by American Physiological Society
Effect of low fibrinogen concentrations on the rheology of human blood in vitro
W. Blattler, P. W. Straub, C. Jeanneret and G. S. Horak
The influence of low concentrations of fibrinogen on the rheology of normal
human blood was investigated with an instrument that permitted simultaneous
determination of viscosity and the state of red blood cell aggregation and
deformation. Fibrinogen, in concentrations of 9-82 mg/100 ml, decreased
blood viscosity at all shear rates below the value obtained with red blood
cells suspended in serum. At concentrations above 116 mg/100 ml viscosity
was increased. Aggregate formation increased progressively as the
fibrinogen concentration increased, necessitating higher dispersing shear
rates. The deformation and alignment of the red cells, occurring at a shear
rate of 230 s-1, was facilitated by low concentrations. The effect of
fibrinogen on low-shear viscosity is explained by the formation of
different kinds of aggregates. At low concentrations, the aggregates
consist of only few cells forming spherelike particles displaying
hemodynamic properties better than those of the single discoid cells. At
normal or high concentrations big rodlike aggregates occur and increase
resistance to flow.
