Urao M, Okuyama H, Drongowski R A, Teitelbaum D H, Coran A G
Section of Pediatric Surgery, C.S. Mott Children's Hospital and the University of Michigan Medical School, Ann Arbor 48109, USA.
J Pediatr Surg. 1997 Oct;32(10):1424-8. doi: 10.1016/s0022-3468(97)90553-4.
BACKGROUND/PURPOSE: The authors have previously reported the occurrence of spontaneous bacterial translocation (BT) and its resolution with age in the newborn rabbit. They have also reported a close correlation between small bowel bacterial colonization (BC-SB) and BT at 1 week of age, suggesting that the presence of luminal bacteria and their production of endotoxins may increase the intestinal permeability. The aim of this study was to evaluate intestinal permeability to small and large molecules in the newborn rabbit and to correlate it with BT.
New Zealand White rabbits (n = 96) 1, 7, 14, 21, and over 120 days (adult) of age were given either C14-labeled ethylene diamine tetraacetic acid (EDTA) (MW 290) or C14-Dextran (MW 70,000) via an orogastric tube at 1 mCi per 100 g of body weight. Five hours later, blood, urine, liver, and intestine were collected, and scintillation counting was performed after solubilization. In a separate series of rabbits (n = 136), the incidence of BT, BC-SB, and small intestinal surface area (SA) were measured.
Total permeability to Dextran decreased with age and was significantly reduced at 14 days of age. In contrast, total permeability to EDTA increased and was maximal in 7- to 14-day-old rabbits and began to decrease at 21 days of age. The incidence of BC-SB rapidly increased at 7 days of age and reached 100% at 14 days of age. The incidence of BT peaked at 7 days of life (30%) and then decreased with age. SA increased rapidly in the first 3 weeks and SA growth rate of 21-day-old rabbits was almost 1,400% compared with 1-day-old rabbits.
This study has shown an age-related reduction of intestinal permeability to large (Dextran) and small (EDTA) molecular weight particles. However, intestinal permeability to EDTA had a different pattern than Dextran, suggesting that there may be different mechanisms of intestinal permeability to different size molecules. Intestinal permeability to EDTA closely correlated with bacterial colonization and bacterial translocation, suggesting that changes in the intestinal bacterial environment may affect the intestinal permeability, possibly by activating the immune system secondary to increases in endotoxins and bacteria.
背景/目的：作者先前已报道新生兔体内自发性细菌移位（BT）的发生情况及其随年龄增长的变化。他们还报道了1周龄时小肠细菌定植（BC-SB）与BT之间存在密切关联，这表明肠腔内细菌的存在及其内毒素的产生可能会增加肠道通透性。本研究的目的是评估新生兔对小分子和大分子的肠道通透性，并将其与BT相关联。
给1日龄、7日龄、14日龄、21日龄及120日龄以上（成年）的新西兰白兔（n = 96）经口胃管给予每100 g体重1 mCi的C14标记乙二胺四乙酸（EDTA，分子量290）或C14-葡聚糖（分子量70,000）。5小时后，采集血液、尿液、肝脏和肠道，溶解后进行闪烁计数。在另一组兔子（n = 136）中，测量BT、BC-SB的发生率以及小肠表面积（SA）。
对葡聚糖的总通透性随年龄增长而降低，在14日龄时显著降低。相比之下，对EDTA的总通透性增加，在7至14日龄的兔子中达到最大值，并在21日龄时开始下降。BC-SB的发生率在7日龄时迅速增加，在14日龄时达到100%。BT的发生率在出生后7天达到峰值（30%），然后随年龄增长而下降。SA在前三周迅速增加，与1日龄兔子相比，21日龄兔子的SA生长率几乎达到1400%。
本研究表明，肠道对大分子（葡聚糖）和小分子（EDTA）的通透性随年龄增长而降低。然而，肠道对EDTA的通透性模式与葡聚糖不同，这表明肠道对不同大小分子的通透性可能存在不同机制。肠道对EDTA的通透性与细菌定植和细菌移位密切相关，这表明肠道细菌环境的变化可能会影响肠道通透性，可能是通过内毒素和细菌增加继发激活免疫系统来实现的。
