Bernhard W, Haagsman H P, Tschernig T, Poets C F, Postle A D, van Eijk M E, von der Hardt H
Department of Pediatric Pulmonology, Medical School Hannover, Germany.
Am J Respir Cell Mol Biol. 1997 Jul;17(1):41-50. doi: 10.1165/ajrcmb.17.1.2594.
Alveolar surfactant is well known for its ability to reduce minimal surface tension at the alveolar air-liquid interface to values below 5 mN/m. In addition, it has been suggested that an analogous conductive airway surfactant is also present in the airways. To elucidate the composition, possible origin, and surface activity of conductive airway phospholipids (PL), we compared in adult porcine lungs the PL classes and phosphatidylcholine (PC) molecular species of nonpurified tracheal aspirate samples with those of bronchoalveolar lavage fluid (BAL), tracheobronchial epithelium, and lung parenchyma. We also analyzed PL and PC composition, protein content, and surface activity of surfactant isolated from tracheal aspirates (SurfTrachAsp), BAL (SurfBAL), and the 27,000 x g pellet of BAL (SurfP27000) by density-gradient centrifugation. Although PL composition revealed contributions of the airways to tracheal aspirates, the composition of PC molecular species of tracheal aspirates was similar to that of BAL and lung parenchyma, but differed considerably from that of airway epithelium. SurfTrachAsp had the same PL and PC composition as SurfBAL and SurfP27000, indicating that this fraction of tracheal aspirates may have originated from the alveoli. Nevertheless, minimal and maximal surface tensions were higher in SurfTrachAsp than in SurfBAL and SurfP27000. Analysis of surfactant proteins A, B, and C (SP-A, SP-B, and SP-C) revealed that SP-A was decreased and SP-B and SP-C were absent, whereas total protein was increased in SurfTrachAsp. We conclude that as compared with alveolar surfactant, PL of SurfTrachAsp show the same composition, but that surface-tension function is impaired and the concentration of surfactant proteins is decreased in SurfTrachAsp.
肺泡表面活性物质因其能够将肺泡气液界面的最小表面张力降低至5 mN/m以下而闻名。此外，有人提出气道中也存在类似的传导气道表面活性物质。为了阐明传导气道磷脂（PL）的组成、可能的来源和表面活性，我们在成年猪肺中比较了未纯化的气管吸出物样本与支气管肺泡灌洗液（BAL）、气管支气管上皮和肺实质的PL类别和磷脂酰胆碱（PC）分子种类。我们还通过密度梯度离心分析了从气管吸出物（SurfTrachAsp）、BAL（SurfBAL）和BAL的27,000 x g沉淀（SurfP27000）中分离的表面活性物质的PL和PC组成、蛋白质含量和表面活性。尽管PL组成显示气道对气管吸出物有贡献，但气管吸出物的PC分子种类组成与BAL和肺实质相似，但与气道上皮有很大差异。SurfTrachAsp与SurfBAL和SurfP27000具有相同的PL和PC组成，表明气管吸出物的这一部分可能起源于肺泡。然而，SurfTrachAsp的最小和最大表面张力高于SurfBAL和SurfP27000。对表面活性物质蛋白A、B和C（SP-A、SP-B和SP-C）的分析表明，SurfTrachAsp中SP-A减少，SP-B和SP-C缺失，而总蛋白增加。我们得出结论，与肺泡表面活性物质相比，SurfTrachAsp的PL显示出相同的组成，但表面张力功能受损，SurfTrachAsp中表面活性物质蛋白的浓度降低。
