Fine K D, Santa Ana C A, Porter J L, Fordtran J S
Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas.
Gastroenterology. 1995 Apr;108(4):983-9. doi: 10.1016/0016-5085(95)90193-0.
BACKGROUND/AIMS: The flow rate of fluid through the proximal small intestine varies widely under normal physiological conditions. The aim of this study was to assess the effect of changes in flow rate on the passive permeability of the aqueous paracellular pathway of the human jejunum.
Normal subjects were studied in vivo during constant perfusion of 30-cm loops of jejunum at flow rates of 5, 10, or 20 mL/min. The permeability ratio of L-xylose/urea was used to assess apparent permeability of the mucosa and to calculate the average pore radius of the aqueous pathway for passive diffusion.
Increasing jejunal flow rate from 5 to 20 mL/min significantly decreased the L-xylose/urea permeability ratio from 0.35 to 0.23 and decreased average calculated pore radius of the diffusion pathway from 13 A to 8 A.
Increases in flow rate in the normal physiological range decrease the estimated pore size of normal healthy jejunal mucosa. Because increasing flow rate is known to increase exposure of luminal fluid to the intervillus space, the results of this study are best explained by postulating that cells lining the sides of villi are less permeable than cells lining the villus tips.
背景/目的：在正常生理条件下，流经近端小肠的液体流速变化很大。本研究的目的是评估流速变化对人空肠水相细胞旁途径被动通透性的影响。
在对正常受试者体内30厘米长的空肠袢以5、10或20毫升/分钟的流速进行持续灌注期间对其进行研究。使用L-木糖/尿素的通透率来评估黏膜的表观通透性，并计算被动扩散水相途径的平均孔径。
将空肠流速从5毫升/分钟提高到20毫升/分钟，显著降低了L-木糖/尿素通透率，从0.35降至0.23，并使扩散途径的平均计算孔径从13埃减小到8埃。
在正常生理范围内流速增加会减小正常健康空肠黏膜的估计孔径。由于已知流速增加会增加肠腔液体与绒毛间隙的接触，本研究结果的最佳解释是假定绒毛侧面的细胞比绒毛顶端的细胞通透性更低。
