Erythrocyte flow and elasticity of microvessels, evaluated by
marginal cell-free layer and flow resistance .
Maeda, Nobuji, Yoji Suzuki, Junya Tanaka, and Norihiko Tateishi.
Department of Physiology, School of Medicine, Ehime University,
Shigenobu, Onsen-gun, Ehime 791-02, Japan
APStracts 3:0247H, 1996.
Flow dynamics of human erythrocytes was compared in elastic (E-) and
hardened (H-) microvessels with inner diameter of 10-40 um. The
thickness of the marginal cell-free layer and the overall flow
resistance were measured using a vascular bed (E-vascular bed)
isolated from rabbit mesentery as well as a 4% paraformaldehyde-fixed
bed (H-vascular bed). (i) In both E- and H-microvessels, the
thickness of the cell-free layer increased with increasing inner
diameter of the microvessels and with decreasing hematocrit
accompanied by an overall decrease of the flow resistance. The
hematocrit-dependent change of cell-free layer thickness was greater
in the E-microvessels than in the H-microvessels. The flow resistance
was always greater in the H-vascular beds than in the E-vascular
beds. (ii) With decreasing erythrocyte deformability induced by
treatment with 2 mM diazene-dicarboxylic acid bis[N,N-dimethylamide],
the thickness of the cell-free layer decreased at a low hematocrit in
the E-microvessels and at a high hematocrit in the H-microvessels,
though the flow resistance increased in both vascular beds. (iii)
Dextran of 70,400 avg mol wt accelerated the formation of the cell
-free layer by inducing erythrocyte aggregation. A drastic increase of
the cell-free layer thickness at 2-4 g/dl dextran in the E
-microvessels and at 1-2 g/dl dextran in the H-microvessels was
accompanied by a significantly lower increase of the flow resistance.
This study concludes that elasticity of microvessels may play an
important role for reducing the overall flow resistance of a vascular
bed, which is modulated by the marginal cell-free layer, itself a
function of the rheological properties of the erythrocytes.
Received 26 February 1996; accepted in final form 10 June 1996.
APS Manuscript Number H186-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96