Review article: duodenal bicarbonate - mucosal protection, luminal chemosensing and acid-base balance
Review article: duodenal bicarbonate - mucosal protection, luminal chemosensing and acid-base balance
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DOI：
10.1111/j1365-2036.2006.00041.x
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发表时间：
2006-12-01
影响因子：
7.6
通讯作者：
Akiba, Y.
中科院分区：
文献类型：
--
作者：
Kaunitz, J. D.;Akiba, Y.
十二指肠充当胃和空肠之间的缓冲区。长度只有25厘米，胃分泌的大量强酸必须转化为后肠腔的中性碱性食糜，产生大量CO2。十二指肠粘膜由低电阻紧密连接连接的上皮细胞组成，形成渗漏的上皮屏障。尽管具有这种渗透性，上皮细胞在管腔矿物酸和高度升高的 Pco(2) 的强烈压力下仍能维持正常功能。碳酸氢根离子独特地保护十二指肠上皮细胞免受酸相关损伤。具体的保护机制可能涉及管腔碳酸氢盐分泌、细胞内pH缓冲和间质缓冲。此外，十二指肠在前肠酸碱平衡中发挥着积极作用，吸收大量的H+和CO2。我们利用活体动物荧光比显微成像以及对十二指肠灌流液进行H+和CO2平衡研究，研究了粘膜保护和酸碱平衡。根据这些数据，我们提出了有关粘膜保护的新假设。
The duodenum serves as a buffer zone between the stomach and the jejunum. Over a length of only 25 cm, large volumes of strong acid secreted by the stomach must be converted to the neutral-alkaline chyme of the hindgut lumen, generating large volumes of CO2.The duodenal mucosa consists of epithelial cells connected by low-resistance tight junctions, forming a leaky epithelial barrier. Despite this permeability, the epithelial cells, under intense stress from luminal mineral acid and highly elevated Pco(2), maintain normal functioning.Bicarbonate ion uniquely protects the duodenal epithelial cells from acid-related injury. The specific protective mechanisms likely involve luminal bicarbonate secretion, intracellular pH buffering and interstitial buffering. Furthermore, the duodenum plays an active role in foregut acid-base homeostasis, absorbing large amounts of H+ and CO2.We have studied mucosal protection and acid-base balance using live-animal fluorescence ratio microimaging and by performing H+ and CO2 balance studies on duodenal perfusates. On the basis of these data, we have formulated novel hypotheses with regard to mucosal protection.