Fahraeus effect and cell screening during tube flow of human blood. I. Effect of variation of flow rate¹

Article type: Research Article

Authors: Gaehtgens, P. | Albrecht, K.H. | Kreutz, F.

Affiliations: Institut für Normale und Pathologische Physiologie der Universitat, 5 Köln-41, Germany

Note: [1] Supported by the Deutsche Forschungsgemeinschaft.

Note: [] Accepted by: Editor A.L. Copley

Abstract: Glass capillaries (I.D. 15–95 μm) were perfused with red cell suspensions in buffered Ringer’s solution using driving pressures which corresponded to wall shear stresses between 5 and 400 dynes/cm2. The hematocrit within the capillaries (HT), in the discharge reservoir (HD), and in the feed reservoir (HF) as well as the volume flow rate through the capillaries were determined. It was observed that variation of flow rate resulted in significant changes of the screening effect (HD/HF < 1) and the Fahraeus effect (HT/HD < 1): cell screening increased and the Fahraeus effect decreased upon reduction of volume flow rate (μ¯-values ranging from 10 to 103 sec−1). The combined effect of both mechanisms resulted in an increase of capillary hematocrit with decreasing flow rate. It is concluded that cellular overvelocity increases with shear stress due to shear-dependent axial concentration of flowing red cells.

DOI: 10.3233/BIR-1978-153-403

Journal: Biorheology, vol. 15, no. 3-4, pp. 147-154, 1978