Gastric mucus and the mucosal barrier.
Gastric mucus and the mucosal barrier.
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DOI：
10.1159/000171168
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发表时间：
1987
影响因子：
2.3
通讯作者：
B. Slomiany;J. Sarosiek;A. Slomiany
中科院分区：
文献类型：
--
作者：
B. Slomiany;J. Sarosiek;A. Slomiany
胃粘膜的一个独特特性是其能够承受胃腔内容物的酸和胃蛋白酶的腐蚀作用。尽管保护机制的确切性质仍然难以捉摸，但一些证据表明它是多方面的。在最常赋予这种保护功能的粘膜成分中，粘稠粘稠的粘液层顽强地粘附在上皮表面和胃上皮的细胞膜上[1-4]。表面粘液层与表面上皮细胞和隐窝细胞的分泌颗粒中包含的预先形成的细胞内粘液处于动态平衡状态，这两种材料共同形成所谓的胃粘膜屏障[1， 2, 5]，虽然粘液提供了粘膜保护的第一道防线，但胃上皮细胞膜以及紧密连接构成了第二道防线。历史上，表面上皮细胞的顶膜及其紧密连接物理上限制 H* 反向扩散到底层粘膜组织的能力被称为“粘膜屏障”[3, 6]。然而，近年来，有充分的证据表明，粘膜完整性是通过表面粘液和碳酸氢盐区、顶细胞膜和粘膜血流等因素的组合来维持的[7-10]。粘膜成分中发生的多种过程提供了多种胃上皮保护机制。这些机制协同工作，确保了粘膜对损伤的固有抵抗力，这种现象现在被称为“胃粘膜屏障”。虽然胃粘膜血流对于处理细胞内 H'、维持 Cl' 运输以及将营养物和氧气转移到表面上皮细胞至关重要 [7,11,12]，但管腔损伤的最初冲击落在粘液层上，粘液层构成胃腔和粘膜表面上皮细胞之间唯一可识别的物理屏障。由于这种策略定位，粘液长期以来被认为在粘膜保护中发挥作用[13-15]。然而，由于缺乏令人信服的实验证据，粘液在保护胃上皮方面的重要性多年来受到了各种不同的质疑。
A unique property of gastric mucosa is its ability to withstand the corrosive action of acid and pepsin of luminal contents. Al though the exact nature of the protective mechanism remains elusive, several lines of evidence indicate that it is multicomponcntial. Among the mucosal components to which this protective function is most often assigned are the viscous and slimy layer of mucus that tenaciously adheres to the epi thelial surfaces, and the cell membranes of gastric epithelium [1-4], The surface mucus layer exists in a dynamic equilibrium with the preformed intracellular mucus contained within the secretory granules of the surface epithelial and crypt cells, and jointly both these materials form the so-called mucous barrier of the stomach [1, 2, 5], While mucus provides the first line of mucosal protection, the cell membranes of gastric epithelium along with tight junctions constitute a sec ond line of defense. Historically, the ability of apical membrane of surface epithelial cells and their tight junctions to physically limit H* back-diffusion into the underlying muco sal tissue have been referred to as the ‘muco sal barrier’[3, 6], In recent years, however, ample evidence has been provided that the mucosal integrity is maintained by a combi nation of such factors as surface mucus and bicarbonate zone, the apical cell membrane, and the mucosal blood flow [7-10]. The mul titude of processes occurring in the mucosal elements offer a wide variety of mechanisms of gastric epithelium protection. These mechanisms, working in concert, assure the inherent resistance of the mucosa to injury and this phenomenon is now termed the ‘gastric mucosal barrier’. While gastric mucosal blood flow is essen tial in the disposal of intracellular H ‘, sus taining Cl'transport, and transfer of nu trients and oxygen to surface epithelial cells [7, 11, 12], the initial brunt of luminal insult falls on the mucus layer which constitutes the only identifiable physical barrier be tween gastric lumen and the surface epithe lial cells of the mucosa. Because of this stra tegic localization, the mucus has long been considered to play a role in the mucosal pro tection [13-15]. Yet, due to the lack of con vincing experimental evidence, the impor tance of mucus in the protection of gastric epithelium met over the years with various