Al-Mehdi A B, Zhao G, Fisher A B
Institute for Environmental Medicine, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA.
Am J Respir Cell Mol Biol. 1998 May;18(5):653-61. doi: 10.1165/ajrcmb.18.5.2834.
We hypothesize that lung ischemic injury is related to cessation of flow leading to endothelial cell membrane depolarization and activation of oxidant-generating systems. Cell membrane potential was assessed in isolated, oxygen ventilated, Krebs-Ringer bicarbonate buffer-dextran-perfused rat lungs by lung surface fluorescence after infusion of bis-oxonol or 5,5',6,6'-tetrachloro-1, 1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1), voltage-sensitive dyes. Surface fluorometry showed increased bis-oxonol fluorescence (34.7 +/- 3.3% above baseline) and decreased JC-1 fluorescence (24.5 +/- 4.5% below baseline) with ischemia, compatible with membrane depolarization. Fluorescence change was initiated within 1-2 min of the onset of ischemia and was rapidly reversible with reperfusion. Fluorescence changes varied with perfusion flow rate; maximal increase occurred with the transition from 1.8 ml/min to zero flow. Elevation of static intravascular pressure resulted in only a minor increase of bis-oxonol fluorescence. In situ subpleural fluorescence microscopy showed that endothelial cells are the major site of the increased bis-oxonol fluorescence signal with ischemia. These results indicate that endothelial cell membrane depolarization represents an early event with lung ischemia. Since the adenosine triphosphate content of lung was unchanged with ischemia in the O2-ventilated lungs, we postulate that membrane depolarization results from elimination of shear stress, possibly via inactivation of flow-sensitive K+-channels.
我们推测，肺缺血性损伤与血流停止有关，血流停止会导致内皮细胞膜去极化并激活产生活性氧的系统。在分离的、氧通气的、用 Krebs-Ringer 碳酸氢盐缓冲液 - 葡聚糖灌注的大鼠肺中，通过注入双羟萘酚或 5,5',6,6'- 四氯 -1,1',3,3'- 四乙基苯并咪唑基碳菁碘化物（JC-1）（电压敏感染料）后，利用肺表面荧光评估细胞膜电位。表面荧光测定显示，缺血时双羟萘酚荧光增加（比基线高 34.7±3.3%），JC-1 荧光减少（比基线低 24.5±4.5%），这与膜去极化相符。荧光变化在缺血开始后 1 - 2 分钟内开始，再灌注时可迅速逆转。荧光变化随灌注流速而变化；从 1.8 毫升/分钟转变为零流量时出现最大增加。静态血管内压力升高仅导致双羟萘酚荧光略有增加。原位胸膜下荧光显微镜检查显示，内皮细胞是缺血时双羟萘酚荧光信号增加的主要部位。这些结果表明，内皮细胞膜去极化是肺缺血的早期事件。由于在氧通气的肺中，肺的三磷酸腺苷含量在缺血时未发生变化，我们推测膜去极化是由于剪切应力消除所致，可能是通过对流量敏感的钾通道失活。
