The Myocardial Cell Surface, Its Histochemistry, and the Effect of Sialic Acid and Calcium Removal on Its Structure and Cellular Ionic Exchange
The Myocardial Cell Surface, Its Histochemistry, and the Effect of Sialic Acid and Calcium Removal on Its Structure and Cellular Ionic Exchange
复制标题
心肌细胞表面、组织化学以及唾液酸和钙去除对其结构和细胞离子交换的影响
作者：
J. Frank;G. Langer;L. M. Nudd;K. Seraydarian
摘要培养的新生大鼠细胞表面、新生大鼠心脏和成年兔心脏对镧、钌红和胶体铁染色剂具有性质相似的反应。所有这些都显示出具有丰富负电荷位点的表面涂层和外部层。具有完整表面结构的细胞不允许镧（La 3+ ）进入细胞内。研究的所有心肌细胞的表面都含有丰富的唾液酸，分布在两个不同的层中，一层位于脂质双层旁边的表面涂层中，另一层位于间质界面的外层中。从细胞表面去除唾液酸可使钙 (Ca 2+ ) 交换性增加 5 至 6 倍。它的去除还允许 La 3+ 进入细胞并取代超过 80% 的细胞 Ca 2+ 。尽管Ca 2+ 和La 3+ 渗透性发生显着变化，唾液酸去除对钾<K + )渗透性没有影响。这表明表面涂层的完整性对于Ca 2+ （和La 3+ ）交换的调节至关重要，但K* 渗透性在双层区域受到控制。细胞暴露于[Ca 2+ ] 0 = 5 /»M 会导致表面发生变化。随着两个唾液酸层的分离以及它们之间形成充满液体的泡，发生外层从表面涂层的剥离。我们建议，Ca 2+ 去除会破坏 Ca 碳水化合物偶联（例如岩藻糖-Ca-岩藻糖桥），这可能会将外部层固定到表面涂层。 Ca 2+ 去除对离子渗透性的影响并不具体。该电池表现出对La 3+ 和K + 的渗透性增加。这表明Ca 2+ 耗尽影响表面结构和双层区域。
SUMMARY The surface of neonatal rat cells in culture, neonatal rat hearts, and adult rabbit hearts have qualitatively similar responses to lanthanum, ruthenium red, and colloidal iron stains. All demonstrate a surface coat and external lamina with abundant negatively charged sites. Cells with intact surface structure do not permit entry of lanthanum (La 3+ ) intracellularly. The surface of all the myocardial cells studied contained abundant sialic acid distributed in two distinct layers, one in the surface coat next to the lipid bilayer, the other in the external lamina at the interstitial interface. The removal of sialic acid from the cellular surface increases calcium (Ca 2+ ) exchangeability 5- to 6-fold. Its removal also permits La 3+ to enter the cell and displace more than 80% of cellular Ca 2+ . Despite these marked alterations in Ca 2+ and La 3+ permeability, sialic acid removal has no effect on potassium <K + ) permeability. This indicates that the integrity of surface coat is critical in the regulation of Ca 2+ (and La 3+ ) exchange but that K* permeability is controlled at the bilayer region. Exposure of the cells to [Ca 2+ ] 0 = 5 /»M produces a change in the surface. A peeling of the external lamina from the surface coat occurs with separation of the two sialic acid layers and the formation of a fluid-filled bleb between them. We propose that Ca 2+ removal ruptures Ca carbohydrate couplings (e.g., fucose-Ca-fucose bridges) which may anchor the external lamina to the surface coat. The effect of Ca 2+ removal on ionic permeability is not specific. The cell demonstrates increased permeability to both La 3+ and K + . This indicates that Ca 2+ depletion affects both the surface structure and the bilayer region.