Occluding junctions in a renal cell line (LLC-PK1) with characteristics of proximal tubular cells.
Occluding junctions in a renal cell line (LLC-PK1) with characteristics of proximal tubular cells.
复制标题
具有近端肾小管细胞特征的肾细胞系 (LLC-PK1) 中的闭塞连接。
DOI：
10.1152/ajprenal.1986.250.4.f734
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Rabito,CA
中科院分区：
文献类型：
--
作者：
Rabito,CA
在融合时，LLC-PK 1单层产生127 Ω X cm 2的跨上皮电阻和极少超过1 mV的自发电位。单分子膜在对称溶液中呈现线性的电流-电压关系。总电导随电解液电解质浓度的增加而线性增加。这些特征表明，控制单层的渗透性的膜是一个单一的膜，它不包含非常弱的带电位点，它是足够厚，以遵守微观电中性的原则。从稀释电位或直接测量单向Na+和Cl-通量确定的钠-氯渗透性分别为0.30和0.38，几乎与肾近端小管直段中获得的比率相同。的电阻的稳态值取决于在孵育介质中的Ca 2+浓度与0.1 mM的表观Km。一个暂时开放的闭塞连接的结果在一个更均匀的分布的Na+依赖的糖转运系统，这是正常情况下局限于上皮细胞的顶膜。这一结果表明，LLC-PK 1单层中的封闭连接作为一种机械屏障，阻止了外源性和内源性膜蛋白的混合。
At confluency, LLC-PK1 monolayers develop a transepithelial electrical resistance of 127 omega X cm2 and a spontaneous electrical potential that very seldom exceeds 1 mV. The monolayer shows a linear current-voltage relation in symmetrical solutions. The total conductance increases linearly with increases in the electrolyte concentration of the bathing solution. These characteristics indicate that the membrane that controls the permeability properties of the monolayer is a single membrane that it does not contain very weakly charged sites and it is sufficiently thick to obey the principle of microscopic electroneutrality. The sodium-to-chloride permeability determined from dilution potentials or from direct measurements of unidirectional Na+ and Cl- flux are 0.30 and 0.38, respectively, almost identical to the ratio obtained in the straight segment of the renal proximal tubule. The steady-state value of the electrical resistance depends on the Ca2+ concentration in the incubation medium with an apparent Km of 0.1 mM. A transitory opening of the occluding junctions results in a more uniform distribution of the Na+-dependent sugar transport system, which is normally confined to the apical membrane of the epithelial cell. This result indicates that the occluding junctions in LLC-PK1 monolayers act as a mechanical barrier, preventing the intermixing of extrinsic as well as intrinsic membrane proteins.