Melligott T F, Beck I T, Dinda P K, Thompson S
Can J Physiol Pharmacol. 1975 Jun;53(3):439-50. doi: 10.1139/y75-063.
Experiments were done for indentification and localization of certain structural changes at different levels of jejunal villus of the hamster during positive and negative water transport across the intestine in vivo and in vitro. Positive transport occurred when the mucosal surface of the intestine was bathed (in vitro experiments) or perfused (in vivo experiments) with isotonic Krebs-Ringer bicarbonate solution containing 10 mM glucose, and negative water transport was achieved by rendering this solution hypertonic with 150 mM mannitol. Results indicate that during positive net water transport the intestine in vivo transported more fluid and exhibited a more conspicuous dilatation of the lateral intercellular spaces (L.I.S.) than did the in vitro preparation. Dilatation of the L.I.S. in both preparations was present only in the apical part of the villus, suggesting that this is the principal site of water absorption. When the mucosal solution was made hypertonic with mannitol, the L.I.S. in the in vivo intestine totally collapsed, whereas in the in vitro intestine these spaces remained open very slightly. These morphological changes correspond well with our finding that in the presence of the hypertonic mucosal solution there was a greater net negative water transport in vivo than in vitro. Incubation of the intestine in the isotonic mucosal solution produced subnuclear swelling of the mid-villus epithelial cells, and this morphological change was associated with an increase in the water content of the tissue. Perfusion of the in vivo intestine with the isotonic solution produced neither the swellings nor the increase in water content of the tissue. In the presence of hypertonic mucosal solution there was a water loss from the tissue both in vivo and in vitro, and these swellings were not observed. These results are discussed in relation to intestinal sugar transport and to the maturity of the epithelial cells, and it is concluded that transport studies on in vitro preparations may provide valid information on a qualitative basis, if not on a strictly quantitative basis.
进行了实验，以鉴定和定位仓鼠空肠绒毛不同水平在体内和体外跨肠进行正性和负性水转运期间的某些结构变化。当肠黏膜表面用含10 mM葡萄糖的等渗碳酸氢盐林格氏溶液浸泡（体外实验）或灌注（体内实验）时发生正性转运，而通过用150 mM甘露醇使该溶液变为高渗来实现负性水转运。结果表明，在正性净水转运期间，体内的肠比体外制剂转运更多的液体，并且侧细胞间隙（L.I.S.）的扩张更明显。两种制剂中L.I.S.的扩张仅存在于绒毛的顶端部分，这表明这是水吸收的主要部位。当用甘露醇使黏膜溶液变为高渗时，体内肠中的L.I.S.完全塌陷，而体外肠中的这些间隙仍略微开放。这些形态学变化与我们的发现非常吻合，即在高渗黏膜溶液存在下，体内的净负性水转运比体外更大。将肠在等渗黏膜溶液中孵育会导致绒毛中部上皮细胞核下肿胀，并且这种形态学变化与组织含水量的增加有关。用等渗溶液灌注体内肠既不会导致组织肿胀也不会导致组织含水量增加。在高渗黏膜溶液存在下，体内和体外的组织都会失水，并且未观察到这些肿胀。结合肠道糖转运和上皮细胞的成熟度对这些结果进行了讨论，得出的结论是，体外制剂的转运研究即使不能在严格定量的基础上，也可能在定性基础上提供有效的信息。
