Minor T, Isselhard W
Division of Surgical Research, University of Bonn, Germany.
Eur Surg Res. 1998;30(2):144-8. doi: 10.1159/000008570.
The intestinal mucosa is one the tissues most sensitive to ischemia. Anoxia of the gut is known to result in an early impairment of cellular permeability and transcapillary barrier function upon reperfusion. In vitro, an increased permeability of endothelial cell monolayers could be shown to be related to a decrease in cellular content of cyclic AMP (cAMP). Thus, the present study was aimed at investigating the role of the cellular cAMP second messenger signal in the context of intestinal ischemia/reperfusion injury after cold preservation. Segments of the upper jejunum were isolated from Wistar rats with vascular pedicle and flushed with 10 ml of UW preservation solution. The intestinal lumen was rinsed with 10-15 ml of UW solution and the organ was stored immersed in UW solution at 4 degrees C for 4 or 18 h. After 18 h of cold ischemic storage structural and functional integrity of the preparation was tested by perfusion via the vascular system with modified Krebs-Henseleit buffer and the intestinal lumen with saline solution (containing 200 mg % of galactose) for 30 min. In half of the experiments, dibutyryl-cAMP a membrane permeable cAMP analogue, was admixed to the flush solution (2 mM). It was found that tissue levels of cAMP linearily decreased to 34% during 18 h of ischemic preservation in UW. Addition of dibutyryl cAMP significantly improved postischemic recovery of the intestinal preparations by decreasing cellular loss of lactic dehydrogenase (18.2 +/- 4.6 vs. 7.6 +/- 2.6 U/I) and improving intestinal absorbtion of galactose from the luminal circuit (0.18 +/- 0.14 vs. 0.36 +/- 0.14 mg %) after 30 min of oxygenated reperfusion, but was not effective to reduce transcapillary water loss into the gut lumen. It is concluded that the anoxia-related decrease of the cellular cAMP level may represent a codeterminator influencing postischemic recovery of the small bowel and that the control of the cAMP signal of ischemic intestines might improve the quality of cold preservation of the gut prior to transplantation.
肠黏膜是对缺血最为敏感的组织之一。已知肠道缺氧会导致再灌注时细胞通透性和跨毛细血管屏障功能早期受损。在体外实验中，可观察到内皮细胞单层通透性增加与细胞内环磷酸腺苷（cAMP）含量减少有关。因此，本研究旨在探讨细胞cAMP第二信使信号在冷保存后肠缺血/再灌注损伤中的作用。从带有血管蒂的Wistar大鼠分离出上段空肠段，并用10毫升UW保存液冲洗。用10 - 15毫升UW溶液冲洗肠腔，然后将器官浸入4℃的UW溶液中保存4或18小时。在冷缺血保存18小时后，通过经血管系统用改良的Krebs - Henseleit缓冲液灌注以及经肠腔用含200mg%半乳糖的盐溶液灌注30分钟来测试标本的结构和功能完整性。在一半的实验中，将膜通透性cAMP类似物二丁酰 - cAMP加入冲洗液（2mM）中。结果发现，在UW中缺血保存18小时期间，cAMP的组织水平线性下降至34%。加入二丁酰 - cAMP通过减少乳酸脱氢酶的细胞损失（18.2±4.6对7.6±2.6U/I）以及改善氧合再灌注30分钟后肠腔半乳糖的吸收（0.18±0.14对0.36±0.14mg%），显著改善了肠标本缺血后的恢复，但在减少跨毛细血管向肠腔内的水分流失方面无效。结论是，与缺氧相关的细胞cAMP水平降低可能是影响小肠缺血后恢复的一个共同决定因素，并且控制缺血肠段的cAMP信号可能会改善移植前肠道冷保存的质量。
