ERYTHROCYTE FLEXIBILITY HEMOCONCENTRATION AND BLOOD FLOW RESISTANCE IN GLASS CAPILLARIES WITH DIAMETERS BETWEEN 6 AND 50 MICRONS

Blood flow resistance in glass capillaries with diameter between 6 and 50 μ was measured by a new method. To determine the very small flow through a micro-capillary, the volume distensibility of a pressure transducer was used. The pressure gradient in all capillaries corresponded to a shear stress of approximately 50 dyn/cm2. Blood samples with high hematocrit (65%), shrinking or swelling of erythrocytes in hyper- or hypotonic solutions, and shape transformation by adding of 2% bile increased relative flow resistance only in the larger capillaries-if compared with normal blood. In capillaries with diameter of 6 μ all blood samples exhibited nearly the same relative viscosity between 2.2 and 2.7. This obvious lack of hemodynamical effect of erythrocyte alteration is explained with the Fåhraeus-Lindquist phenomena. © 1968 Springer-Verlag.