Allen A, Leonard A J, Sellers L A
Department of Physiological Sciences, Medical School, University of Newcastle upon Tyne, England.
J Clin Gastroenterol. 1988;10 Suppl 1:S93-8.
A layer of water-insoluble mucus gel has been shown to form a continuous cover over the gastroduodenal mucosal surfaces, of median thickness of 180 micron in stomach in humans. This adherent mucus is the first line in mucosal defence against the natural aggressors, acid and pepsin, in the lumen. Mucus gel provides a stable unstirred layer that supports surface neutralisation of acid by mucosal bicarbonate. Mucus gel is a diffusion barrier to pepsin in the lumen, preventing proteolysis of the underlying epithelial cells. There is, however, a dynamic balance between digestion by pepsin of the mucus layer at its luminal aspect and secretion of new mucus by the epithelium. There is evidence that, in peptic ulcer disease, the rate of peptic degradation of the mucus barrier is increased. Exogenous damaging agents such as ethanol and aspirin permeate the gel matrix of the mucus barrier, rapidly damaging the underlying epithelium. The subsequent reepithelialisation process is protected by a gelatinous coat over ten times thicker than the original adherent mucus layer. This gelatinous coat is primarily a fibrin-based gel with necrotic cells and mucus.
已证明一层水不溶性黏液凝胶在胃十二指肠黏膜表面形成连续覆盖层，在人类胃中其平均厚度为180微米。这种附着性黏液是黏膜抵御管腔内天然侵害物（胃酸和胃蛋白酶）的第一道防线。黏液凝胶提供了一个稳定的未搅动层，支持黏膜碳酸氢盐对酸的表面中和作用。黏液凝胶是管腔内胃蛋白酶的扩散屏障，可防止其对下方上皮细胞的蛋白水解作用。然而，在管腔侧，胃蛋白酶对黏液层的消化与上皮细胞分泌新黏液之间存在动态平衡。有证据表明，在消化性溃疡疾病中，黏液屏障的胃蛋白酶降解速率会增加。乙醇和阿司匹林等外源性损伤剂可渗透黏液屏障的凝胶基质，迅速损伤下方上皮。随后的上皮再形成过程受到一层比原始附着性黏液层厚十多倍的凝胶状涂层的保护。这种凝胶状涂层主要是一种含有坏死细胞和黏液的纤维蛋白基凝胶。
