REGULATION OF HEPATIC SINUSOIDAL PERFUSION IN SHOCK

缺血、炎症或其他情况下的肝脏损伤 与休克相关的疾病仍然是一个严重的临床问题。成长中的身体 最新证据表明微循环是 病理，这可能是确定严重程度的主要因素 肝脏损伤。然而，微血管损伤的机制 发生的情况还没有被很好地理解。最近的证据表明， 肝脏微血管损伤的可能靶血管是 正弦波。传统上，减少的正弦流被认为是 上游较大船只关闭的结果或对 正弦波。然而，最近的研究表明，正弦波是 能够主动的、分级的和可逆的收缩从而有助于 直接调节肝窦血流灌注。这样做的长期目标是 因此，建议是检验正弦收缩的假设 促成了一种迄今未知的调节功能的机制 肝脏灌流和这一系统的失调是一个主要的 肝缺血再灌注后肝微血管损伤的决定因素 发炎。为了检验这一假说，本文提出了四个具体目标。 首先，确定哪些生理血管活性物质作用于正弦。 抵抗地点。第二，测试是否控制个别正弦波 正弦收缩灌流是一种主动调节机制。 正常的肝脏。这一目标还将测试正弦电阻是否 调节是局部灌流匹配的重要机制 代谢需求。第三，测试这个系统的失调是否通过一个 局部收缩和扩张物质表达的不平衡 (例如，内皮素和一氧化氮)可能导致微血管衰竭 在缺血或发炎之后。最后，我们将测试一个 正弦收缩反应性的增加通过激活 正弦衬里细胞也有助于增加正弦 缺血后血管收缩导致微血管损伤 发炎。这些研究将集中在肝脏的活动上。 星状细胞作为窦收缩的主要效应器，但将 也要测试Kupffer细胞作为中介或 扩张器对外源性血管活性物质的反应 或应激后的内源性反应。这些研究将使用 活体显微镜与离体灌流术的结合 肝脏以量化微血管反应与Norther和 Western印迹分析、免疫组织化学和原位杂交 测定血管活性物质和标志物的水平和定位 效应器细胞的激活。归根结底，这些研究应该有助于 实质上有助于理解正弦血流灌注是如何调节的 以及这一调节的改变如何导致 肝脏损伤。

Liver injury following ischemia, inflammation or other conditions associated with shock remains a serious clinical problem. A growing body of recent evidence points to the microcirculation as a primary target for pathology which may be the major factor in determining the severity of liver injury. Nevertheless, the mechanisms by which microvascular injury occurs are not well understood. Recent evidence indicates that the probable target vessel for microvascular injury in the liver is the sinusoid. Classically, decreased sinusoidal flow has been considered to be the result of either shutdown of larger vessels upstream or overt injury to the sinusoids. Recently, however, it has been shown that the sinusoids are capable of active, graded and reversible constriction thus contributing directly to regulation of sinusoid perfusion. The long range goal of this proposal is, thus, to test the hypothesis that sinusoidal constriction contributes to a heretofore unknown mechanism for regulating functional liver perfusion and that dysregulation of this system is a major determinant of hepatic microvascular injury following ischemia or inflammation. Four specific aims are proposed to test this hypothesis. First, determine which physiologic vasoactive substances act at sinusoidal resistance sites. Second, test whether control of individual sinusoid perfusion by sinusoidal constriction is an actively regulated mechanism in the normal liver. This aim will also test whether sinusoidal resistance regulation is an important mechanism for local matching of perfusion to metabolic demand. Third, test whether dysregulation of this system via an imbalance in the local expression of constrictor and dilator substances (e.g. endothelin and nitric oxide) may contribute to microvascular failure following ischemia or inflammation. Finally, we will test whether an increase in contractile responsiveness of the sinusoid via activation of sinusoidal lining cells also contributes to increased sinusoidal constriction leading to microvascular injury following ischemia or inflammation. These studies will focus on the activity of the hepatic stellate cells as the primary effector of sinusoid constriction but will also test the possible contribution of kupffer cells as intermediaries or amplifiers in the constrictor response to exogenous vasoactive substances or endogenous responses following stress. These studies will use a combination of intravital microscopy both in vivo and in isolated perfused livers to quantitate the microvascular responses along with Norther and Western blot analysis, immunohistochemistry, and in situ hybridization to determine the level and localization of vasoactive substances and markers of effector cell activation. Ultimately, these studies should contribute substantially to the understanding of how sinusoidal perfusion is regulated in the normal liver and how alterations in this regulation can lead to liver injury.