title: Erythrocyte flow and elasticity of microvessels evaluated by marginal cell-free layer and flow resistance.
abstract: Flow dynamics of human erythrocytes was compared in elastic (E) and hardened (H) microvessels with inner diameters of 10-40 microns. The thickness of the marginal cell-free layer and the overall flow resistance were measured with a vascular bed isolated from rabbit mesentery (E vascular bed) as well as with a 4% paraformaldehyde-fixed bed (H vascular bed). 1) 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 in the flow resistance. The hematocrit-dependent change of the 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. 2) With decreasing erythrocyte deformability induced by treatment with 2 mM diazenedicar-boxylic 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, although the flow resistance was increased in both vascular beds. 3) Dextran of 70,400 average molecular weight accelerated the formation of the cell-free layer by inducing erythrocyte aggregation. A drastic increase in the cell-free layer thickness at 2-4 g/dl of dextran in the E microvessels and at 1-2 g/dl of dextran in the H microvessels was accompanied by a significantly lower increase in the flow resistance. This study concludes that the 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.
authors.affiliation: Department of Physiology, School of Medicine, Ehime University, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Maeda
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.forename: J
authors.initials: J
authors.lastname: Tanaka
authors.forename: N
authors.initials: N
authors.lastname: Tateishi
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000502:physiology*; D003911:Dextrans / Q000494:pharmacology; D004548:Elasticity; D004903:Erythrocyte Aggregation; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology*; D006400:Hematocrit; D006801:Humans; D008833:Microcirculation; D011817:Rabbits; D014655:Vascular Resistance
chemical_list: D003911:Dextrans