葡萄糖刺激人体空肠在体内被动吸收小溶质的机制。
Mechanism by which glucose stimulates the passive absorption of small solutes by the human jejunum in vivo.
作者信息
Fine K D, Santa Ana C A, Porter J L, Fordtran J S
机构信息
Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas.
出版信息
Gastroenterology. 1994 Aug;107(2):389-95. doi: 10.1016/0016-5085(94)90163-5.
BACKGROUND/AIMS: Active absorption of glucose stimulates passive absorption of small solutes. Part of this effect may be caused by glucose-induced water absorption. Increased water absorption can enhance passive solute absorption by solvent drag and by passive diffusion if the luminal solute concentration increases as water is removed from the lumen. The purpose of this research was to quantitate the contribution of these two forces when glucose enhances the absorption of L-xylose.
METHODS
The effect of solvent drag on L-xylose absorption was determined by measuring the effect of water absorption stimulated by hypotonicity on L-xylose absorption when the L-xylose concentration was constant. The effect of diffusion on L-xylose absorption was determined by measuring the effect of L-xylose concentration on L-xylose absorption when water absorption was nil.
RESULTS
Glucose increased L-xylose absorption by 1.8 mmol.h-1 x 30 cm-1 (from 1.4 to 3.2 mmol.h-1 x 30 cm-1). The increase attributable to solvent drag was 1.03 mmol.h-1 x 30 cm-1; the increase attributable to passive diffusion was 0.75 mmol.h-1 x 30 cm-1.
CONCLUSIONS
When glucose stimulates the passive absorption of L-xylose, 57% of the increase can be attributed to solvent drag and 42% to passive diffusion. Because the combined effect of these two forces can account for 99% of the observed effect, virtually all of the glucose effect on L-xylose absorption can be explained by glucose-induced water absorption.
背景/目的：葡萄糖的主动吸收会刺激小溶质的被动吸收。这种效应的部分原因可能是葡萄糖诱导的水吸收。如果管腔溶质浓度随着水从管腔中被去除而增加，水吸收的增加可通过溶剂拖曳和被动扩散增强被动溶质吸收。本研究的目的是定量这两种力量在葡萄糖促进 L-木糖吸收时的贡献。
方法
当 L-木糖浓度恒定时，通过测量低渗刺激的水吸收对 L-木糖吸收的影响来确定溶剂拖曳对 L-木糖吸收的作用。当水吸收为零时，通过测量 L-木糖浓度对 L-木糖吸收的影响来确定扩散对 L-木糖吸收的作用。
结果
葡萄糖使 L-木糖吸收增加了 1.8 mmol·h⁻¹×30 cm⁻¹（从 1.4 增加到 3.2 mmol·h⁻¹×30 cm⁻¹）。归因于溶剂拖曳的增加为 1.03 mmol·h⁻¹×30 cm⁻¹；归因于被动扩散的增加为 0.75 mmol·h⁻¹×30 cm⁻¹。
结论
当葡萄糖刺激 L-木糖的被动吸收时，增加量的 57%可归因于溶剂拖曳，42%归因于被动扩散。由于这两种力量的联合作用可解释观察到的效应的 99%，实际上葡萄糖对 L-木糖吸收的所有效应都可以用葡萄糖诱导的水吸收来解释。
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