Guo Y, Krumwiede M, White J G, Wangensteen O D
Department of Physiology, University of Minnesota, Minneapolis 55455, USA.
Am J Physiol. 1996 Feb;270(2 Pt 1):L224-31. doi: 10.1152/ajplung.1996.270.2.L224.
We previously found that HOCl, produced from neutrophil products in infected airways, decreases electrical resistance (R) of rabbit tracheal epithelium. Interestingly, HOCl at 6 mM, a reasonable concentration in diseased airways, decreased R without apparent cell damage. This study sought to determine whether this noncytotoxic dose of HOCl causes morphological changes that correlate with the decrease in R. Excised rabbit tracheas were treated with 6 mM HOCl for 15 min, before and after which epithelial R was determined. Epithelial tissue was then fixed and prepared for transmission electron microscopy, immunofluorescent labeling of F-actin or the tight junction protein ZO-1, or freeze fracture to examine tight junction strands. HOCl treatment caused a 50% decrease in R. Electron micrographs showed no cell, cell membrane, or tight junction changes. By laser confocal microscopy, 6 mM HOCl did not affect the distribution of F-actin or ZO-1. However, morphometric analysis of freeze-fracture replicas showed that tight junction strand number was significantly decreased from 7.06 +/- 0.09 to 4.79 +/- 0.11 and junctional width was significantly decreased from 0.306 +/- 0.007 to 0.214 +/- 0.006 microns. These latter changes may have contributed to the observed decrease in epithelial R.
我们之前发现，感染气道中中性粒细胞产物产生的次氯酸（HOCl）会降低兔气管上皮的电阻（R）。有趣的是，6 mM的HOCl（患病气道中的合理浓度）可降低R，且无明显细胞损伤。本研究旨在确定这种无细胞毒性剂量的HOCl是否会引起与R降低相关的形态学变化。将切除的兔气管用6 mM HOCl处理15分钟，处理前后测定上皮R。然后固定上皮组织，制备用于透射电子显微镜检查、F-肌动蛋白或紧密连接蛋白ZO-1的免疫荧光标记，或冷冻断裂以检查紧密连接链。HOCl处理使R降低了50%。电子显微镜照片显示细胞、细胞膜或紧密连接无变化。通过激光共聚焦显微镜观察，6 mM HOCl不影响F-肌动蛋白或ZO-1的分布。然而，对冷冻断裂复制品的形态计量分析表明，紧密连接链的数量从7.06±0.09显著减少到4.79±0.11，连接宽度从0.306±0.007显著减少到0.214±0.006微米。后一种变化可能导致了观察到的上皮R降低。
