The ultrastructure and chemistry of the luminal plasma membrane of the mammalian urinary bladder: a structure with low permeability to water and ions.
The ultrastructure and chemistry of the luminal plasma membrane of the mammalian urinary bladder: a structure with low permeability to water and ions.
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哺乳动物膀胱管腔质膜的超微结构和化学：水和离子渗透性低的结构。
DOI：
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发表时间：
1974
期刊：
影响因子：
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通讯作者：
R. C. Warren
中科院分区：
文献类型：
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作者：
R. M. Hicks;B. Ketterer;R. C. Warren
哺乳动物膀胱上皮是尿液和组织液之间尿素、水和小电荷离子自由流动的有效屏障。在本文中，我们提出的证据表明，这种通透性屏障被动地依赖于限制上皮细胞尿液表面的不寻常的、厚的、坚硬的膜的结构。这种膜的正常结构是独一无二的。增厚的斑块由延伸到膜深处的十二聚体亚基组成的六角形晶格组成，由更薄的、无结构的窄带隔开。用尿素、盐酸胍或十二烷基硫酸钠处理可能会破坏或扭曲晶格的规则结构。在化学上，这种膜也是了不起的。其脂类成分中含有脑苷脂，具有明显的降水渗作用。胆固醇加强了这种作用，在膀胱收缩和扩张的机械压力下，胆固醇可能对维持凝聚的脂肪层很重要。蛋白质组分也是不寻常的，因为它具有高的脯氨酸含量，这一点的意义在膜结构和功能的背景下进行了讨论。目前还不可能将膜的标记亚单位结构与其蛋白质组分联系起来，尽管大颗粒质量的粘蛋白化合物可能位于膜的厚的、浓染的、带负电的表面层中。因此，这种膜在结构和功能上都是令人惊叹的。这些特性反过来必须依赖于其脂类和蛋白质成分之间的复杂相互作用，而这些相互作用本身就是不寻常的。
The epithelium of the mammalian urinary bladder is an effective barrier to the free flux of urea, water and small charged ions between urine and tissue fluids. In this paper we present evidence to show that this permeability barrier passively depends on the structure of the unusual, thick, rigid membrane which limits the urinary surface of the epithelial cells. The normal structure of this membrane is unique. Thickened plaques, composed of a hexagonal lattice of dodecameric subunits which extend through the depth of the membrane, are separated by thinner, unstructured, narrow bands. The regular structure of the lattice may be disrupted or distorted by treatment with urea, guanidine hydrochloride or sodium dodecyl sulphate. Chemically the membrane is also remarkable. Its lipid component contains cerebroside, which apparently has an important effect in lowering water permeability. This effect is reinforced by cholesterol, which may be important for the maintenance of a condensed lipid layer during the mechanical stresses of bladder contraction and dilation. The protein component also is unusual in having a high proline content, and the significance of this is discussed in the context of membrane structure and function. At the moment it is not possible to relate the marked subunit structure of the membrane to its protein component although the large particle mass mucoprotein compound, as yet uncharacterized, may be located in the thick, densely staining, negatively charged surface lamina of the membrane. This membrane is thus remarkable in both its structure and its function. These properties in turn must depend on complex interactions between its lipid and protein components which are themselves unusual.