House S D, Lipowsky H H
Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Microvasc Res. 1987 Nov;34(3):363-79. doi: 10.1016/0026-2862(87)90068-9.
The effects of leukocyte-endothelium adhesion on microhemodynamics were studied in cat mesentery under control conditions and following tissue suffusion with the chemotactic agent N-formyl-methionyl-leucyl-phenylalanine (FMLP). The results indicate that under normophysiological conditions there is little or no leukocyte-endothelium adhesion in arterioles and venules. Tissue suffusion with FMLP significantly increases the number of adhering leukocytes in venules, but not in arterioles. Analysis of the number of adhering leukocytes (in venules) as a function of wall shear rate suggested that increased adhesion of leukocytes was primarily due to elevated adhesive forces and not the result of decreases in dispersal forces, i.e., wall shear stress. From measurements of upstream to downstream pressure drop, red cell velocity, and microvessel hematocrit in 16 unbranched venules, no significant changes in diameter (mean of 39.9 +/- 7.8 (SD) micron), intravascular pressure gradient (0.59 +/- 0.40 X 10(-2) cm H2O/micron), nor microvessel hematocrit (31.0 +/- 9.8%) occurred in response to FMLP. There were significant decreases in upstream pressure (8%) and estimated bulk flow (28%) as well as significant increases in the number of adhering leukocytes, from 1.5 +/- 2.8 to 11.4 +/- 8.3 cells/100 micron, and vessel resistance (81%). Changes in hemodynamics were found to be more pronounced in venules with small diameters. The observed response to FMLP suggests that changes in hemodynamics during leukocyte-endothelium adhesion can be accounted for by a decrease in the effective diameter due to obstruction of the lumen by WBCs, and that adhesive interactions between WBCs and endothelium are a major determinant of blood flow resistance in the microcirculation.
在对照条件下以及在用趋化剂N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（FMLP）灌注组织后，研究了猫肠系膜中白细胞与内皮细胞黏附对微血流动力学的影响。结果表明，在正常生理条件下，小动脉和小静脉中几乎没有白细胞与内皮细胞的黏附。用FMLP灌注组织可显著增加小静脉中黏附白细胞的数量，但对小动脉无此影响。对黏附白细胞数量（在小静脉中）与壁剪切率的函数分析表明，白细胞黏附增加主要是由于黏附力升高，而非分散力（即壁剪切应力）降低的结果。通过对16条无分支小静脉的上游至下游压降、红细胞速度和微血管血细胞比容的测量，未发现FMLP引起直径（平均为39.9±7.8（标准差）微米）、血管内压力梯度（0.59±0.40×10⁻²厘米水柱/微米）或微血管血细胞比容（31.0±9.8%）有显著变化。上游压力（8%）和估计的总体流量（28%）显著降低，黏附白细胞数量从1.5±2.8增加到11.4±8.3个细胞/100微米，血管阻力增加（81%）。血流动力学变化在小直径小静脉中更为明显。观察到的对FMLP的反应表明，白细胞与内皮细胞黏附期间的血流动力学变化可归因于白细胞阻塞管腔导致有效直径减小，并且白细胞与内皮细胞之间的黏附相互作用是微循环中血流阻力的主要决定因素。
