Gao X, Kouklis P, Xu N, Minshall R D, Sandoval R, Vogel S M, Malik A B
Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.
Am J Physiol Lung Cell Mol Physiol. 2000 Dec;279(6):L1218-25. doi: 10.1152/ajplung.2000.279.6.L1218.
We determined the role of vascular endothelial (VE)-cadherin complex in regulating the permeability of pulmonary microvessels. Studies were made in mouse lungs perfused with albumin-Krebs containing EDTA, a Ca(2+) chelator, added to study the VE-cadherin junctional disassembly. We then repleted the perfusate with Ca(2+) to restore VE-cadherin integrity. Confocal microscopy showed a disappearance of VE-cadherin immunostaining in a time- and dose-dependent manner after Ca(2+) chelation and reassembly of the VE-cadherin complex within 5 min after Ca(2+) repletion. We determined the (125)I-labeled albumin permeability-surface area product and capillary filtration coefficient (K(fc)) to quantify alterations in the pulmonary microvessel barrier. The addition of EDTA increased (125)I-albumin permeability-surface area product and K(fc) in a concentration-dependent manner within 5 min. The permeability response was reversed within 5 min after repletion of Ca(2+). An anti-VE-cadherin monoclonal antibody against epitopes responsible for homotypic adhesion augmented the increase in K(fc) induced by Ca(2+) chelation and prevented reversal of the response. We conclude that the disassembled VE-cadherins in endothelial cells are mobilized at the junctional plasmalemmal membrane such that VE-cadherins can rapidly form adhesive contact and restore microvessel permeability by reannealing the adherens junctions.
我们确定了血管内皮（VE）-钙黏蛋白复合物在调节肺微血管通透性中的作用。研究采用向灌注含白蛋白- Krebs液的小鼠肺中添加Ca²⁺螯合剂乙二胺四乙酸（EDTA），以研究VE-钙黏蛋白连接的解体。然后我们在灌注液中补充Ca²⁺以恢复VE-钙黏蛋白的完整性。共聚焦显微镜显示，Ca²⁺螯合后，VE-钙黏蛋白免疫染色呈时间和剂量依赖性消失，Ca²⁺补充后5分钟内VE-钙黏蛋白复合物重新组装。我们测定了¹²⁵I标记白蛋白的通透面积乘积和毛细血管滤过系数（K(fc)），以量化肺微血管屏障的改变。添加EDTA在5分钟内以浓度依赖性方式增加了¹²⁵I-白蛋白通透面积乘积和K(fc)。Ca²⁺补充后5分钟内通透性反应逆转。一种针对负责同型黏附的表位的抗VE-钙黏蛋白单克隆抗体增强了Ca²⁺螯合诱导的K(fc)增加，并阻止了反应的逆转。我们得出结论，内皮细胞中解体的VE-钙黏蛋白在连接质膜处被动员，使得VE-钙黏蛋白能够迅速形成黏附接触，并通过重新退火黏附连接来恢复微血管通透性。
