TRANSCELLULAR WATER TRANSPORT IN LUNG ALVEOLAR EPITHELIUM THROUGH MERCURY-SENSITIVE WATER CHANNELS
TRANSCELLULAR WATER TRANSPORT IN LUNG ALVEOLAR EPITHELIUM THROUGH MERCURY-SENSITIVE WATER CHANNELS
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DOI：
10.1073/pnas.91.11.4970
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发表时间：
1994-05-24
影响因子：
11.1
通讯作者：
VERKMAN, AS
中科院分区：
文献类型：
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作者：
FOLKESSON, HG;MATTHAY, MA;VERKMAN, AS
水在气隙和毛细血管间室之间的运动对于维持呼吸过程中的气隙水合作用和重吸收多余的肺泡液体是重要的。我们已经获得了免疫细胞化学和功能的证据，质膜水通道负责水运输在完整的肺。北方和定量免疫印迹分析显示大鼠肺中CHIP 28（28 kDa的通道形成整合膜蛋白）水通道的高表达;免疫细胞化学显示CHIP 28定位于上皮细胞质膜。在新鲜分离的大鼠肺泡II型上皮细胞中的渗透性水渗透性（P-f）的停流光散射测量表明0.015 +/- 0.002 cm/s（10 ℃）的高P-f，其具有弱的温度依赖性（活化能，4 kcal/mol），并且被0.5 mM HgCl 2可逆地抑制78 +/- 4%。采用绵羊肺原位灌流模型，测定了完整肺内水运动的途径。向远端气隙滴注含放射性碘化白蛋白和[C-14]甘露醇的高渗盐水（900 mOsm）后，通过采样气隙液体测量血液至气隙的水转运。在七组实验中，空气空间渗透压和放射性碘化白蛋白平衡的t（1/2）为0.85 +/- 0.1 min。在对侧肺灌注0.5 mM氯化汞，t（1/2）增加到2.7 +/- 0.4 min;氯化汞的抑制作用被完全逆转5 mM 2-巯基乙醇。这些结果提供了直接的证据，跨细胞运动的水通过汞敏感的水通道在完整的肺肺泡上皮细胞。
The movement of water between the air space and capillary compartments is important for the maintenance of air space hydration during respiration and for reabsorption of excess alveolar fluid. We have obtained immunocytochemical and functional evidence that plasma-membrane water channels are responsible for water transport in the intact lung. Northern and quantitative immunoblot analysis showed high expression of CHIP28 (channel-forming integral membrane protein of 28 kDa) water channels in rat lung; immunocytochemistry showed CHIP28 localization to epithelial cell plasma membranes. Stopped-flow light scattering measurements of osmotic water permeability (P-f) in freshly isolated rat alveolar type II epithelial cells indicated a high P-f of 0.015 +/- 0.002 cm/s (10 degrees C) that was weakly temperature-dependent (activation energy, 4 kcal/mol) and reversibly inhibited by 78 +/- 4% by 0.5 mM HgCl2. An in situ-perfused sheep lung model was used to determine the route for water movement in intact lung. Blood-to-air-space water transport was measured by sampling air space fluid after instillation into distal air spaces of hyperosmolar saline (900 mOsm) containing radioiodinated albumin and [C-14]mannitol. In seven sets of experiments, air space osmolality and radioiodinated albumin equilibrated with a t(1/2) of 0.85 +/- 0.1 min. In the contralateral lung perfused with 0.5 mM HgCl2, t(1/2) increased to 2.7 +/- 0.4 min; the inhibitory effect of HgCl2 was fully reversed by 5 mM 2-mercaptoethanol. These results provide direct evidence for transcellular movement of water across the alveolar epithelium in intact lung through mercury-sensitive water channels.