Functional ion channels in pulmonary alveolar type I cells support a role for type I cells in lung ion transport
Functional ion channels in pulmonary alveolar type I cells support a role for type I cells in lung ion transport
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DOI：
10.1073/pnas.0600855103
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发表时间：
2006-03-28
影响因子：
11.1
通讯作者：
Eaton, DC
中科院分区：
文献类型：
--
作者：
Johnson, MD;Bao, HF;Eaton, DC
肺内有效的气体交换取决于肺泡上皮细胞内薄层（平均0.2 μ m）液体中液体量的调节。液体流量由跨肺泡上皮的离子转运调节，肺泡上皮由肺泡I型（TI）和II型（TII）细胞组成。公认的范例是TII细胞，其覆盖小于5%的肺内表面积，转运Na+和Cl-，而TI细胞，其覆盖> 95%的表面积，提供水吸收的途径。在这里，我们提出的数据，TI细胞含有功能性上皮Na+通道（ENaC），pimozide敏感的阳离子通道，K+通道，和囊性纤维化跨膜调节。Till细胞含有ENaC和囊性纤维化跨膜调节因子，但几乎没有pimozide敏感的阳离子通道。这些发现导致了肺中离子和水转运的修正范例，其中（i）Na+和Cl-转运发生在整个肺泡上皮（TI和TII细胞）上，而不是仅发生在TII细胞上;以及（h）由于TI细胞的表面积非常大，TI细胞负责肺中的大部分跨上皮Na+转运。
Efficient gas exchange in the lungs depends on regulation of the amount of fluid in the thin (average 0.2 mu m) liquid layer lining the alveolar epithelium. Fluid fluxes are regulated by ion transport across the alveolar epithelium, which is composed of alveolar type I (TI) and type II (TII) cells. The accepted paradigm has been that TII cells, which cover < 5% of the internal surface area of the lung, transport Na+ and Cl- and that TI cells, which cover > 95% of the surface area, provide a route for water absorption. Here we present data that TI cells contain functional epithelial Na+ channels (ENaC), pimozide-sensitive cation channels, K+ channels, and the cystic fibrosis transmembrane regulator. Till cells contain ENaC and cystic fibrosis transmembrane regulator, but few pimozide-sensitive cation channels. These findings lead to a revised paradigm of ion and water transport in the lung in which (i) Na+ and Cl- transport occurs across the entire alveolar epithelium (TI and TII cells) rather than only across TII cells; and (h) by virtue of their very large surface area, TI cells are responsible for the bulk of transepithelial Na+ transport in the lung.