AJP - Heart and Circulatory Physiology, Vol 268, Issue 1 25-H32, Copyright © 1995 by American Physiological Society

ARTICLES

Transient rheological behavior of blood in low-shear tube flow: velocity profiles and effective viscosity

C. Alonso, A. R. Pries, O. Kiesslich, D. Lerche and P. Gaehtgens
Department of Physiology, Freie Universitat Berlin, Germany.

Velocity profiles of human blood flowing through vertical and horizontal glass tubes (25-100 microns ID) were measured as a function of time following a sudden reduction of wall shear stress (tau w) from a high value to values ranging from 2 to 100 mPa. Cell velocities at various radial positions were determined off-line from video recordings by digital image analysis. In vertical tubes, symmetric velocity profiles were obtained that developed increasing bluntness with time, particularly at lower tau w and in smaller tubes. In horizontal tubes, velocity profiles developed strong asymmetry as a function of time. Red blood cell (RBC) sedimentation was associated with uniform low flow velocities in the concentrating cell sediment, whereas faster flow and almost parabolic profiles were observed in the supernatant plasma region. Calculations of effective blood viscosity showed a decrease with time at low tau w in vertical tubes but an increase in horizontal tubes. The differences between profile shape and effective viscosity in vertical and horizontal tubes disappeared at tau w > 50 mPa. These findings are related to the cross-sectional distribution of RBC, which depends on RBC aggregation and sedimentation.

This article has been cited by other articles:

				S. Kim, A. S. Popel, M. Intaglietta, and P. C. Johnson Aggregate formation of erythrocytes in postcapillary venules Am J Physiol Heart Circ Physiol, February 1, 2005; 288(2): H584 - H590. [Abstract] [Full Text] [PDF]

				O. Yalcin, M. Uyuklu, J. K. Armstrong, H. J. Meiselman, and O. K. Baskurt Graded alterations of RBC aggregation influence in vivo blood flow resistance Am J Physiol Heart Circ Physiol, December 1, 2004; 287(6): H2644 - H2650. [Abstract] [Full Text] [PDF]

				J. J. Bishop, A. S. Popel, M. Intaglietta, and P. C. Johnson Effects of erythrocyte aggregation and venous network geometry on red blood cell axial migration Am J Physiol Heart Circ Physiol, August 1, 2001; 281(2): H939 - H950. [Abstract] [Full Text] [PDF]

				J. J. Bishop, P. R. Nance, A. S. Popel, M. Intaglietta, and P. C. Johnson Erythrocyte margination and sedimentation in skeletal muscle venules Am J Physiol Heart Circ Physiol, August 1, 2001; 281(2): H951 - H958. [Abstract] [Full Text] [PDF]

				J. J. Bishop, P. R. Nance, A. S. Popel, M. Intaglietta, and P. C. Johnson Effect of erythrocyte aggregation on velocity profiles in venules Am J Physiol Heart Circ Physiol, January 1, 2001; 280(1): H222 - H236. [Abstract] [Full Text] [PDF]

				K. Osterloh, P. Gaehtgens, and A. R. Pries Determination of microvascular flow pattern formation in vivo Am J Physiol Heart Circ Physiol, April 1, 2000; 278(4): H1142 - H1152. [Abstract] [Full Text] [PDF]

				B. P. Helmke, S. N. Bremner, B. W. Zweifach, R. Skalak, and G. W. Schmid-Schonbein Mechanisms for increased blood flow resistance due to leukocytes Am J Physiol Heart Circ Physiol, December 1, 1997; 273(6): H2884 - H2890. [Abstract] [Full Text] [PDF]

				A. R. Pries, T. W. Secomb, H. Jacobs, M. Sperandio, K. Osterloh, and P. Gaehtgens Microvascular blood flow resistance: role of endothelial surface layer Am J Physiol Heart Circ Physiol, November 1, 1997; 273(5): H2272 - H2279. [Abstract] [Full Text] [PDF]