Chen B T, Yeates D B
Departments of Medicine and Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
Am J Respir Crit Care Med. 2000 Nov;162(5):1715-22. doi: 10.1164/ajrccm.162.5.9912120.
We hypothesized that water transport associated with fluxes of Na(+) and Cl(-) across airway epithelium coexists and is distinct from osmotically driven water transport. To investigate this, we anesthetized and mechanically ventilated dogs (n = 8) with warm humid air. The trachea of each dog was sequentially challenged with 250-mOsm and 950-mOsm mannitol aerosols given 30 min apart. Respiratory tract fluid output (RTFO) was collected at the posterior commissure at 6-min intervals. The percentages of mannitol in the RTFO were determined with fluorescent tracers and were subtracted from the RTFO to give airway secretory output (ASO). Unbound [Na(+)] and [Cl(-)] in the RTFO were measured. Following the 250-mOsm mannitol challenge, the ASO as well as its Na(+) and Cl(-) contents increased. Following the 950-mOsm challenge, there was a further increase in ASO without any further increases in Na(+) and Cl(-) contents. Increased mucociliary transport accounted for only part of the increase in ASO. These data are consistent with the hypothesis that net water transport into the airway lumen is the vectorial sum of the water fluxes associated with actively driven intracellular Na(+) and Cl(-) transport and the water flux due to osmosis.
我们假设，与气道上皮细胞中Na(+)和Cl(-)通量相关的水转运与渗透驱动的水转运共存且不同。为了对此进行研究，我们用温暖潮湿的空气对狗（n = 8）进行麻醉并进行机械通气。每隔30分钟依次用250毫渗摩尔和950毫渗摩尔的甘露醇气雾剂对每只狗的气管进行刺激。每隔6分钟在咽后间隙收集呼吸道液体输出量（RTFO）。用荧光示踪剂测定RTFO中甘露醇的百分比，并从RTFO中减去该百分比以得出气道分泌输出量（ASO）。测量RTFO中未结合的[Na(+)]和[Cl(-)]。在250毫渗摩尔甘露醇刺激后，ASO及其Na(+)和Cl(-)含量增加。在950毫渗摩尔刺激后，ASO进一步增加，而Na(+)和Cl(-)含量没有进一步增加。黏液纤毛运输增加仅占ASO增加的一部分。这些数据与以下假设一致，即进入气道腔的净水转运是与主动驱动的细胞内Na(+)和Cl(-)转运相关的水通量以及渗透引起的水通量的矢量和。
