Comparison of screen filtration pressure and low-shear viscosity of blood

Abstract

Screen filtration pressure (SFP) and blood viscosity (at shear rates of 0.05 sec-1 and 5 sec-1) were determined simultaneously on dog blood. Addition of high molecular weight dextran (250,000) caused increases in both viscosity and SFP, and the latter showed a plateau during the 10-sec period of measurement. When 5-hydroxytryptamine together with adenosine diphosphate were added to blood and when blood was obtained after severe hemorrhage, viscosity did not change but SFP increased sharply and showed no tendency to approach a steady state. Such sharp increases in SFP were not observed when the experiments were performed on blood without buffy coat. It is concluded that SFP of blood containing high molecular weight dextran reflects viscosity at relatively high shear rates and that the sharp increases in SFP following the addition of 5-hydroxytryptamine and adenosine diphosphate as well as following exsanguination are due to the adhesiveness of platelets and/or leucocytes to the screen. Note: (With the Technical Assistance of Kathleen Prichard) adenosine diphosphate; dextran; hemorrhage; 5-hydroxytryptamine Submitted on January 8, 1965