Adherence and Viscosity of Blood Contacting Foreign Surfaces and the Plasmatic Zone in Blood Circulation

Abstract

THE cell-free marginal zone of plasma in vessels of living animals, due to the axial accumulation of red blood cells, was already known to Haller and Spallanzani in the eighteenth century¹. The formation of this zone was later studied by Poiseuille¹ in arteries, veins and capillaries in various species of the living animal. He found that, with increased velocity, the thickness of this layer was augmented. Recently, in the course of investigations on the flow of blood columns using a tilting viscometer (Scott Blair, G. W., personal communication), we made the following observation. If an index of human or rabbit blood, containing 0.01 mgm. heparin/ml. as anticoagulant, be permitted to flow down a large capillary tube held at varying angles from the vertical, then films of blood of varying thickness can usually be seen macroscopically on the wall after the column has passed. This finding led to investigations on the flow of varying indexes of blood, plasma and serum in glass tubes 0.5–1.4 mm. in diameter, where the Reynolds number is so small that turbulence is out of the question. We found that the adherence of fluids from moving indices in such capillary tubes can be determined by simply measuring the reduction in the length of the index after it has travelled a certain distance, and then calculating the thickness of the adherent layer. By this method, we found that this phenomenon is not limited to blood, but can also be detected when cell-free plasma or serum is used instead. Moreover, this adherence is not dependent on glass surfaces, as we found it in tubes coated with silicone, ‘Lusteroid’, ‘Perspex’ and paraffin as well.