Flow dynamics of erythrocytes was compared using microvascular bed isolated from rabbit mesentery and glass capillaries. A part of microvascular bed was isolated rabbit mesentery under anesthesia. Human erythrocytes modified their deformability with 0-2mM diamide by crosslinking spectrins in the membrane cytoskeletal proteins were perfused through superior mesenteric artery. The erythrocyte flow in microvessels was observed under an inverted microscope with a video system and analyzed with an image processor. A flashlight was used for the quantitation of deformed erythrocytes. Erythrocyte velocity was determined by a dual-spot cross-correlation technique.
As the feeding hematocrit through a microvessel or glass capillary (the inner diameter, -30μm) decreased, the thickness of cell-free layer increased. The increment of cell-free layer with decreasing hematocrit was greater in microvessels than in glass capillary. As the flow velocity of erythrocytes increased, erythrocytes were more elongated to parachute-like shape in both tubes less than 9μm in inner diameter. Furthermore, increasing the degree of spectrin crosslinking (i.e., by decreasing erythrocyte deformability), erythrocytes were less elongated. The elongation of erythrocytes to parachute-like shape was always greater in glass capillaries than in microvessels.
In conclusion, flow behavior of erythrocytes in glass capillaries are essentially different from that in microvessels, even if qualitatively similar each other.
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