Fluid and ion transport in corneal endothelium: insensitivity to modulators of Na(+)-K(+)-2Cl- cotransport.
Fluid and ion transport in corneal endothelium: insensitivity to modulators of Na(+)-K(+)-2Cl- cotransport.
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角膜内皮中的液体和离子传输：对 Na( )-K( )-2Cl- 共转运调节剂不敏感。
DOI：
10.1152/ajpcell.1997.273.5.c1480
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Peters,MI
中科院分区：
文献类型：
--
作者：
Riley,MV;Winkler,BS;Starnes,CA;Peters,MI
通过测定角膜水化变化和内皮细胞层对86rb的摄取，探讨Na+-K+-2Cl -共转运在角膜内皮离子和液体转运中的作用。分离的、完整的兔角膜在内皮表面与碳酸氢盐（）-林格溶液混合后保持正常的水合作用，这是由于活性离子和基质组织外的液体运输以及体液从房水中泄漏到基质组织之间的平衡。当将速尿和布美他尼加入到超融合培养基中时，它们不会改变这种平衡。布美他尼使培养角膜内皮细胞对86rb的摄取增加了25%，但布美他尼没有改变乌阿拜存在时（比对照组少70%）的摄取。在无Na+的培养基中，86rb的吸收量减少了58%，而在无Cl−的培养基中则没有变化。Calyculin A是一种蛋白磷酸酶抑制剂和Na+-K+-Cl -共转运的激活剂，对86rb的摄取没有影响。高渗（345 mosmol/kg）使摄取略有增加，而低渗（226 mosmol/kg）使摄取减少33%。当介质中存在布美他尼时，这两种变化都没有显著差异。结果表明，Na+-K+-2Cl -共转运体活性不表现在角膜内皮细胞中，也不参与该细胞层的离子和流体运输。它在培养的内皮细胞中的存在可能反映了该蛋白在生长、增殖和分化中的重要性。
The role of Na+-K+-2Cl−cotransport in ion and fluid transport of the corneal endothelium was examined by measuring changes in corneal hydration and uptake of86Rb by the endothelial cell layer. Isolated, intact rabbit corneas maintain normal hydration when they are superfused at the endothelial surface with bicarbonate ()-Ringer solutions as a result of equilibrium between active ion and fluid transport out of the stromal tissue and leak of fluid into stromal tissue from the aqueous humor. Furosemide and bumetanide did not alter this equilibrium when they were added to the superfusion medium. Uptake of86Rb by the endothelium of the incubated cornea was increased 25% by bumetanide, but uptake in the presence of ouabain (70% less than that of controls) was not changed by bumetanide. In Na+-free medium, uptake of86Rb was reduced by 58%, but it was unchanged in Cl−-free medium. Calyculin A, a protein phosphatase inhibitor and activator of Na+-K+-Cl−cotransport, was without effect on86Rb uptake. Hypertonicity (345 mosmol/kg) increased uptake slightly, whereas hypotonicity (226 mosmol/kg) caused a 33% decrease. Neither of these changes was significantly different when bumetanide was present in the media. It is concluded that Na+-K+-2Cl−cotransporter activity is not exhibited by the in situ corneal endothelium and does not play a role in the ion and fluid transport of this cell layer. Its presence in cultured endothelial cells may reflect the reported importance of this protein in growth, proliferation, and differentiation.