INTESTINAL PERFUSION AND PERMEABILITY IN SEPSIS

已经假设，在屏障功能中的错乱 肠道使危重病人容易发生菌血症， 真菌血症和内毒素血症。上皮屏障的完整性可以 通过测量其对某些水溶性的渗透性来进行评估 化合物，如51Cr-EDTA。肠道上皮的渗透性 亲水性溶质是由功能状态决定的 细胞间紧密连接(闭合带；ZO)。最近的数据表明 ZO在解剖学上和功能上都与细胞骨架相连。 其他结果表明，该委员会的组织完整性 细胞骨架依赖于维持足够的细胞内水平 三磷酸腺苷。因为细胞缺氧和氧化应激都会干扰 ATP合成，我们假设内毒素(LPS)诱导的 肠粘膜高通透性是由肠细胞内ATP耗竭引起的。 因此，我们将研究缺血和氧化剂诱导的粘膜ATP 耗竭是内毒素对肠道不良反应的机制 上皮通透性。拟议的研究将利用一头猪 内毒素血症模型，令人满意地再现了许多血流动力学 败血症休克在复苏患者中的表现。粘膜 通透性将通过测量血浆到管腔的清除量来定量 ~(51)Cr-EDTA。将使用多根导线测量粘膜氧合 克拉克型表面电极阵列，允许监测02 组织的多个微半球(半径约20微米)的张力。 使用这些方法，我们将评估内毒素对 粘膜氧合、三磷酸腺苷含量和通透性。此外，我们还将 确定内毒素诱导的粘膜高通透性是否可以通过 维持正常的上皮氧合，要么通过泵灌流 肠道供氧血的血管供应或肠腔的灌流 肠道内含氧缓冲液。此外，我们还将调查 通过评估别嘌醇(一种黄嘌呤氧化酶)的效果来评估氧化剂 抑制物)或氧自由基清除剂对粘膜通透性和 内毒素动物体内的ATP含量。最后，我们将评估 粘膜缺氧或氧化应激对粘膜ATP含量和通透性的影响 在正常的猪身上。这些研究应该会为我们提供对 脓毒症黏膜高通透性的发病机制 内毒素血症。

It has been hypothesized that derangements in the barrier function of the gut predispose critically ill patients to the development of bacteremia, fungemia, and endotoxicosis. The integrity of the epithelial barrier can be assessed by measuring its permeability to certain water-soluble compounds, such as 51Cr-EDTA. The permeability of the gut epithelium to hydrophilic solutes is determined by the functional status of the intercellular tight junctions (zonula occludens; ZO). Recent data suggest that the ZO is anatomically and functionally linked to the cytoskeleton. Other results indicate that the organizational integrity of the cytoskeleton depends upon the maintenance of adequate intracellular levels of ATP. Since both cellular hypoxia and oxidant stress can interfere with ATP synthesis, we have hypothesized that lipopolysaccharide (LPS)-induced mucosal hyperpermeability is caused by ATP depletion in enterocytes. Accordingly, we will investigate ischemia- and oxidant-induced mucosal ATP depletion as mechanisms for the adverse effect of endotoxin on gut epithelial permeability. The proposed studies will utilize a porcine endotoxicosis model that satisfactorily reproduces many of the hemodynamic manifestations of septic shock in resuscitated patients. Mucosal permeability will be quantitated by measuring the plasma-to-lumen clearance of 51Cr-EDTA. Mucosal oxygenation will be measured using a multiwire Clark-type surface electrode array that permits the monitoring of 02 tensions in multiple microscopic hemispheres (radius~20 uM) of tissue. Using these methods, we will assess the time-dependent effects of LPS on mucosal oxygenation, ATP content, and permeability. In addition, we will determine whether LPS-induced mucosal hyperpermeability can be prevented by maintaining normal epithelial oxygenation, either by pump-perfusing the vascular supply of the gut with oxygenated blood or perfusing the lumen of the gut with oxygenated buffer. Also, we will investigate the role of oxidants by assessing the effects of allopurinol (a xanthine oxidase inhibitor) or oxygen free-radical scavengers of mucosal permeability and ATP content in endotoxic animals. Finally, we will assess the affects of mucosal hypoxia or oxidant stress on mucosal ATP content and permeability in normal pigs. These studies should provide new insights into the mechanisms responsible for mucosal hyperpermeability in sepsis and endotoxicosis.