Physiological measurements of luminal stirring in the dog and human small bowel.
Physiological measurements of luminal stirring in the dog and human small bowel.
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DOI：
10.1172/jci114873
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发表时间：
1990-11
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影响因子：
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通讯作者：
Michael D. Levitt;J. K. Fume;Alessandra Strocchi;B. W. Anderson;David Levitt
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文献类型：
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作者：
Michael D. Levitt;J. K. Fume;Alessandra Strocchi;B. W. Anderson;David Levitt
认为管腔内容物搅拌不良导致的吸收阻力（RLum）相当于人小肠中大于600 μ m的未搅拌层。我们通过评估两种快速吸收探针（葡萄糖和[14 C]华法林）的吸收率，测量了清醒犬空肠中的RLum。当RLum表示为未搅拌层时，未搅拌层的最大厚度（假设上皮细胞阻力可忽略不计）仅为约35和50微米，灌注速率分别为26和5 ml/min。根据先前的葡萄糖吸收研究计算的人空肠最大未搅拌层厚度的平均值仅为40微米（范围：23至65微米）。由于在低浓度葡萄糖吸收过程中上皮电阻似乎可以忽略不计，因此40微米的最大未搅拌层应接近人小肠中葡萄糖的真实值。我们的结论是，在狗和人的快速吸收的化合物的未搅拌层小于以前报道的值的十分之一，但该层仍然可能是快速转运的化合物的吸收速率限制步骤。
The resistance to absorption resulting from poor stirring of luminal contents (RLum) is considered to be equivalent to an unstirred layer of greater than 600 microns in the human small intestine. We measured RLum in the jejunum of conscious dogs by assessing the absorption rate of two rapidly absorbed probes, glucose, and [14C]warfarin. When RLum was expressed as an unstirred layer, the maximal thickness of the unstirred layer (assuming negligible epithelial cell resistance) was only approximately 35 and 50 microns for perfusion rates of 26 and 5 ml/min, respectively. Maximal unstirred layer thickness for the human jejunum, calculated from previous studies of glucose absorption, yielded a mean value of only 40 microns (range: 23 to 65 microns). Since epithelial resistance appears to be negligible during absorption of low concentrations of glucose, the maximal unstirred layer of 40 microns should be close to the true value for glucose in the human small intestine. We conclude that the unstirred layer for rapidly absorbed compounds in dogs and man are less than one-tenth of previously reported values, but this layer still may remain the rate limiting step in absorption of rapidly transported compounds.