Krugliak P, Hollander D, Schlaepfer C C, Katz K D, Dadufalza V D, Ma T Y
Division of Gastroenterology, University of California, Irvine.
Gastroenterology. 1990 Oct;99(4):1001-7. doi: 10.1016/0016-5085(90)90619-c.
Permeability changes of polyethylene glycol 400 have been seen in patients with inflammatory bowel diseases. Because the colon can be involved in inflammatory bowel disease, the mechanisms, kinetics, and influence of intraluminal factors on polyethylene glycol 400 permeation of perfused colonic segments of rats were studied. The absorption rate of polyethylene glycol 400 was linearly related to its luminal concentration (r = 0.94), suggesting that passive diffusion is a significant mechanism involved in polyethylene glycol 400 absorption. Changing the perfusate pH from 6.0 to 7.5 did not affect water absorption or polyethylene glycol 400 permeation. Increasing luminal osmolarity significantly decreased water and polyethylene glycol 400 absorption (P less than 0.01). The relationship between polyethylene glycol 400 and water absorption at different luminal osmolarities was linear (r = 0.97). At luminal osmolarity of 0.3 osm/L, 14.3% of polyethylene glycol 400 absorption was mediated by passive diffusion and 85.7% was mediated by convection. The solvent drag reflection coefficient for polyethylene glycol 400 in the colon was 0.03. Taurocholic acid (10 mmol/L) and chenodeoxycholic acid (5 mmol/L) decreased polyethylene glycol 400 and water absorption (P less than 0.01). Addition of 1 micrograms/mL of 16,16-dimethyl prostaglandin E2, 2 mmol/L of dibutyryladenosine-3',5'-cyclic monophosphate, or 10 mmol/L of aminophylline significantly decreased water and polyethylene glycol 400 absorption (P less than 0.01). These studies demonstrate that polyethylene glycol 400 permeation of the colon is mediated by both passive diffusion and solvent drag. Convective absorption is the major mechanism of polyethylene glycol 400 permeation of the colon. Polyethylene glycol 400 permeation is modified by bile acids, prostaglandins, and cyclic nucleotides through changes in water flux.
炎症性肠病患者中已观察到聚乙二醇400的通透性变化。由于结肠可累及炎症性肠病，因此研究了腔内因素对大鼠灌注结肠段中聚乙二醇400渗透的机制、动力学及影响。聚乙二醇400的吸收速率与其腔内浓度呈线性相关（r = 0.94），表明被动扩散是聚乙二醇400吸收的重要机制。将灌注液pH从6.0变为7.5不影响水吸收或聚乙二醇400渗透。增加腔内渗透压显著降低水和聚乙二醇400的吸收（P < 0.01）。不同腔内渗透压下聚乙二醇400与水吸收之间的关系呈线性（r = 0.97）。在腔内渗透压为0.3 Osm/L时，聚乙二醇400吸收的14.3%由被动扩散介导，85.7%由对流介导。结肠中聚乙二醇400的溶剂拖曳反射系数为0.03。牛磺胆酸（10 mmol/L）和鹅去氧胆酸（5 mmol/L）降低聚乙二醇400和水的吸收（P < 0.01）。添加1 μg/mL的16,16 - 二甲基前列腺素E2、2 mmol/L的二丁酰腺苷 - 3',5'-环磷酸或10 mmol/L的氨茶碱显著降低水和聚乙二醇400的吸收（P < 0.01）。这些研究表明，结肠对聚乙二醇400的渗透由被动扩散和溶剂拖曳介导。对流吸收是结肠对聚乙二醇400渗透的主要机制。聚乙二醇400的渗透通过胆汁酸、前列腺素和环核苷酸对水通量的改变而受到影响。
