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This Article Full Text Full Text (PDF) Supplemental Videos All Versions of this Article: 297/2/H583    most recent 00352.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Sakai, H. Articles by Tsuchida, E. PubMed PubMed Citation Articles by Sakai, H. Articles by Tsuchida, E.

Peculiar flow patterns of RBCs suspended in viscous fluids and perfused through a narrow tube (25 µm)

¹Research Institute for Science and Engineering, Waseda University, and ²Department of Life Science and Medical Bioscience, Graduate School of Science and Engineering, Waseda University, Tokyo; and ³Department of Physiology, School of Medicine, Ehime University, Ehime, Japan

Submitted 10 April 2009 ; accepted in final form 5 June 2009

Red blood cells (RBCs) generally deform to adopt a parachute-like, torpedo-like, or other configuration to align and flow through a capillary that is narrower than their major axis. As described herein, even in a narrow tube (25 µm) with diameter much larger than that of a capillary, flowing RBCs at 1 mm/s align axially and deform to a paraboloid shape in a viscous Newtonian fluid (505 kDa dextran medium) with viscosity of 23.4–57.1 mPa·s. A high-speed digital camera image showed that the silhouette of the tip of RBCs fits a parabola, unlike the shape of RBCs in capillaries, because of the longer distance of the RBC-free layer between the tube wall and the RBC surface (8.8 µm). However, when RBCs are suspended in a "non-Newtonian" viscous fluid (liposome-40 kDa dextran medium) with a shear-thinning profile, they migrate toward the tube wall to avoid the axial lining, as "near-wall-excess," which is usually observed for platelets. This migration results from the presence of flocculated liposomes at the tube center. In contrast, such near-wall excess was not observed when RBCs were suspended in a nearly Newtonian liposome-albumin medium. Such unusual flow patterns of RBCs would be explainable by the principle; a larger particle tends to flow near the centerline, and a small one tends to go to the wall to flow with least resistance. However, we visualized for the first time the complete axial aligning and near-wall excess of RBCs in the noncapillary size tube in some extreme conditions.

hemorheology; erythrocytes; viscometry; artificial red cells; microcirculation