Jenkins A P, Menzies I S, Nukajam W S, Creamer B
Gastrointestinal Laboratory, Rayne Institute, St Thomas' Hospital, London, U.K.
Scand J Gastroenterol. 1994 Sep;29(9):820-5. doi: 10.3109/00365529409092517.
We have previously shown that small oral doses of poorly absorbed solute can significantly reduce absorption of test sugars in normal volunteers. To confirm these results and investigate the underlying mechanism, the effects of lactulose on absorption of three test sugars in subjects with ileostomies were studied.
Ten fasted subjects with ileostomies ingested an isosmolar test solution containing 2.5 g 3-O-methyl-D-glucose, 5.0 g D-xylose, 1.0 g L-rhamnose, and 50 microCi 51Cr-labelled ethylenediaminetetraacetic acid together with a blue dye transit marker. Urine was collected for time periods of 0-5 h and 5-24 h, to measure excretion of absorbed sugars, and ileostomy effluent was saved from 0-5 h and from 5 h until blue dye transit marker was no longer present, to measure small-bowel output of unabsorbed sugars. After 1 week the test was repeated, including 5 g lactulose in the test solution.
Inclusion of lactulose in the test solution significantly reduced the 5 h and 24 h urine excretion of L-rhamnose and D-xylose but not that of 3-O-methyl-D-glucose and increased 0- to 5-h and total ileostomy output of L-rhamnose and D-xylose but not of 3-O-methyl-D-glucose. The presence of lactulose also reduced the time for first appearance of the blue dye transit marker in the effluent and increased effluent volume together with output of electrolyte.
Poorly absorbed solute reduces intestinal absorption by retention of fluid and electrolyte, with subsequent intraluminal dilution and acceleration of transit.
我们之前已经表明，口服小剂量吸收不良的溶质可显著降低正常志愿者中试验糖类的吸收。为了证实这些结果并探究潜在机制，我们研究了乳果糖对回肠造口术患者三种试验糖类吸收的影响。
10名空腹的回肠造口术患者摄入一种等渗试验溶液，该溶液含有2.5克3 - O - 甲基 - D - 葡萄糖、5.0克D - 木糖、1.0克L - 鼠李糖以及50微居里51Cr标记的乙二胺四乙酸，同时还摄入一种蓝色染料转运标记物。收集0 - 5小时和5 - 2４小时的尿液，以测量吸收糖类的排泄情况，并收集0 - 5小时以及从5小时直至蓝色染料转运标记物不再出现时的回肠造口流出物，以测量未吸收糖类的小肠排出量。1周后重复该试验，试验溶液中加入5克乳果糖。
试验溶液中加入乳果糖显著降低了L - 鼠李糖和D - 木糖在5小时和24小时的尿排泄量，但未降低3 - O - 甲基 - D - 葡萄糖的尿排泄量，且增加了L - 鼠李糖和D - 木糖在0至5小时以及回肠造口流出物总量中的排出量，但未增加３ - O - 甲基 - D - 葡萄糖的排出量。乳果糖的存在还缩短了流出物中蓝色染料转运标记物首次出现的时间，并增加了流出物体积以及电解质排出量。
吸收不良的溶质通过保留液体和电解质来减少肠道吸收，随后导致肠腔内稀释并加速转运。
