Ward B J, Donnelly J L
Department of Anatomy, Queen Mary and Westfield College, London, United Kingdom.
Cardiovasc Res. 1993 Mar;27(3):384-9. doi: 10.1093/cvr/27.3.384.
The aim was to determine the effect of hypoxia on the ultrastructure of the endothelial glycocalyx of cardiac capillaries.
Isolated rat hearts were perfused with oxygenated or hypoxic Krebs solution for 30 min after equilibration with oxygenated medium. They were then perfused with a cationic marker (ruthenium red, lanthanum nitrate, or cationised ferritin) to delineate the cardiac endothelial glycocalyx in the electron microscope. With ruthenium red and lanthanum, perfusions were carried out both in the presence and absence of bovine serum albumin. Ferritin perfused hearts were used to quantify changes in the glycocalyx as a result of hypoxia and to measure the cross sectional area of the endothelial cells.
In all the hearts perfused with well oxygenated solution, all three markers showed an even, electron dense layer on the luminal surface of the capillaries. With ruthenium red and lanthanum (but not with ferritin), the marker was occasionally observed throughout the length of the interendothelial clefts and on the albuminal surface. After 30 min hypoxic perfusion, both ruthenium red and lanthanum showed disruption and irregular clumping of the glycocalyx, with or without albumin. Ferritin, however, showed a sparse and uneven layer. Measurements of endothelial cell area showed that some cells from hypoxic hearts were swollen when compared with controls. Measurements of the percentage of luminal membrane covered by ferritin molecules showed a significant loss of glycocalyx in hypoxic hearts. There was, however, no correlation between loss of glycocalyx and endothelial cell swelling.
The endothelial cell glycocalyx of continuous capillaries is sensitive to changes in PO2. The disruption of this surface coat may explain the reported increase in capillary permeability in hypoxia.
本研究旨在确定缺氧对心脏毛细血管内皮糖萼超微结构的影响。
将离体大鼠心脏先用含氧培养基平衡，然后用含氧或缺氧的 Krebs 溶液灌注 30 分钟。接着用阳离子标记物（钌红、硝酸镧或阳离子化铁蛋白）灌注，以便在电子显微镜下描绘心脏内皮糖萼。使用钌红和镧进行灌注时，分别在有和没有牛血清白蛋白的情况下进行。用铁蛋白灌注的心脏用于量化缺氧导致的糖萼变化，并测量内皮细胞的横截面积。
在所有用充分含氧溶液灌注的心脏中，所有三种标记物在毛细血管腔表面均显示出均匀的电子致密层。使用钌红和镧（但不包括铁蛋白）时，偶尔会在内皮细胞间隙全长以及白蛋白表面观察到标记物。缺氧灌注 30 分钟后，无论有无白蛋白，钌红和镧均显示糖萼破坏和不规则聚集。然而，铁蛋白显示出稀疏且不均匀的层。内皮细胞面积测量结果表明，与对照组相比，缺氧心脏中的一些细胞肿胀。铁蛋白分子覆盖的腔膜百分比测量结果显示，缺氧心脏中糖萼显著丢失。然而，糖萼丢失与内皮细胞肿胀之间没有相关性。
连续毛细血管的内皮细胞糖萼对 PO2 变化敏感。这种表面涂层的破坏可能解释了缺氧时毛细血管通透性增加的报道。
