How to Measure CFTR-Dependent Bicarbonate Transport: From Single Channels to the Intact Epithelium
How to Measure CFTR-Dependent Bicarbonate Transport: From Single Channels to the Intact Epithelium
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DOI：
10.1007/978-1-61779-117-8_30
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发表时间：
2011-01-01
期刊：
影响因子：
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通讯作者：
Gray, Michael A.
中科院分区：
文献类型：
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作者：
Hug, Martin J.;Clarke, Lane L.;Gray, Michael A.
碳酸氢盐在我们的身体里有很多功能。它是维持血液和细胞内生理pH值的主要缓冲液。它对于营养物质的适当消化和复杂蛋白质混合物（如消化酶和粘蛋白）在上皮分泌物中的增溶也是必不可少的。经上皮HCO3-运输也驱动许多上皮组织的净液体分泌，包括胃肠道和生殖道以及气道。事实上，碳酸氢盐分泌缺陷是大多数囊性纤维化患者胰腺病理生理学的标志。CF基因中的一些致病突变在异源系统中表达时导致碳酸氢盐转运受损，但不是全部。最近开发的突变CFTR的药理学调节剂已经证明了激活氯化物运输的能力，但对它们是否也增加碳酸氢盐的分泌知之甚少。因此，在研究小分子对CFTR功能的影响时，测定碳酸氢盐的转运是必要的。然而，由于离子的混沌性，通过CFTR测量碳酸氢盐的绝对浓度及其渗透率绝非易事。在本章中，我们将回顾一些可用于测量碳酸氢盐通过单离子通道、单个细胞和完整上皮层运输的技术。
Bicarbonate serves many functions in our body. It is the predominant buffer maintaining a physiological pH in the blood and within our cells. It is also essential for proper digestion of nutrients and solubilization of complex protein mixtures, such as digestive enzymes and mucins, in epithelial secretions. Transepithelial HCO3- transport also drives net fluid secretion in many epithelial tissues including those in the gastrointestinal and reproductive tracts as well as the airways. Indeed, defective bicarbonate secretion is a hallmark of the pathophysiology in the pancreas of most patients suffering from cystic fibrosis. Some, but not all, disease-causing mutations in the CF gene lead to impaired bicarbonate transport when expressed in heterologous systems. Recently developed pharmacological modulators of mutant CFTR have demonstrated an ability to activate chloride transport but little is known about whether they also increase the secretion of bicarbonate. It is therefore essential to assay bicarbonate transport when studying the effect of small molecules on CFTR function. However, due to the chaotropic nature of the ion, the measurement of the absolute bicarbonate concentration and its permeability through CFTR is far from trivial. In this chapter we will review some of the techniques available to measure bicarbonate transport through single ion channels, individual cells, and intact epithelial layers.