Isenberg J I, Hogan D L, Thomas F J
Scand J Gastroenterol Suppl. 1986;125:106-9. doi: 10.3109/00365528609093825.
The human proximal duodenum serves as the crucible for the neutralization of gastric acid. Methods have been developed and validated that permit isolation of 4-cm segments of either the proximal or distal duodenum. These isolated segments were free of contamination from gastric, pancreatic, and biliary secretions. At rest the healthy human proximal duodenum produced approximately 175 mumol cm-h: or, assuming that the duodenal bulb is approximately 4 cm in length, 700 mumol h. The distal duodenum (the third part) produced significantly less bicarbonate, approximately 25 mumol/cm-h. HCl produced a prompt and sustained increase in bicarbonate output from both duodenal segments. Bicarbonate output was less in the distal duodenum, indicating a proximal-to-distal gradient. Synthetic prostaglandin E1 caused a dose-related increase in output. Substitution of the NaCl perfusate with Na2SO4 produced a brief decrease, suggesting a chloride bicarbonate exchange mechanism. Vasoactive intestinal polypeptide significantly increased proximal duodenal bicarbonate output. Bicarbonate production by the duodenal mucosa is probably an important defensive factor in maintaining mucosal integrity.
人类十二指肠近端是胃酸中和的关键部位。现已开发并验证了一些方法，可用于分离十二指肠近端或远端4厘米长的节段。这些分离出的节段不受胃、胰腺和胆汁分泌物的污染。在静息状态下，健康人的十二指肠近端每厘米每小时产生约175微摩尔的碳酸氢盐；或者假设十二指肠球部长度约为4厘米，则每小时产生700微摩尔。十二指肠远端（第三部分）产生的碳酸氢盐明显较少，约为每厘米每小时25微摩尔。盐酸可使两个十二指肠节段的碳酸氢盐分泌迅速且持续增加。十二指肠远端的碳酸氢盐分泌较少，表明存在从近端到远端的梯度。合成前列腺素E1可使分泌量呈剂量相关增加。用硫酸钠替代氯化钠灌流液会导致短暂减少，提示存在氯-碳酸氢盐交换机制。血管活性肠肽可显著增加十二指肠近端的碳酸氢盐分泌。十二指肠黏膜产生碳酸氢盐可能是维持黏膜完整性的重要防御因素。
