HEPATIC AMINO ACID TRANSPORT DURING SERIOUS INFECTION

在严重感染期间，肝脏成为原则 氨基酸摄取器官，一种适应性反应， 支持急性期蛋白质合成并赋予 对宿主的生存有利。 肝氨基增加 脓毒症期间的酸提取主要归因于 增强质膜转运活性。 的焦点 拟议的研究是探讨非- 肝实质细胞作为血浆来源 引发质膜氨基酸增加的介质 在实质细胞中摄取。 我们特别 对实质细胞中的氨基酸摄取感兴趣。 我们特别感兴趣的是谷氨酰胺 因为它被证明是“有条件的必要的” 在某些分解代谢状态下， 膜可以代表其在其生物学特性中的限速步骤。 新陈代谢. 我们实验室的初步数据显示 增强肝脏谷氨酰胺转运的能力， 它是维生素E介导的，是生存所必需的。 分离的大鼠肝细胞将用于检查 单个细胞因子、激素、条件 来自非实质细胞的培养基和来自内毒素的血清- 给药动物的氨基酸转运。 审查 炎性细胞因子/激素的作用，离体大鼠 将实质细胞与IL-1，TNF，IL-6， PGE 2和地塞米松单独和联合使用， 通过测定谷氨酰胺和丙氨酸转运活性。 到 阐明窦状隙细胞在反应中的作用， 非实质细胞（NPC：枯否细胞，内皮细胞 细胞）将被分离并培养L+内毒素或TNF-α。 存在和不存在中和剂时的α 有效的细胞因子的抗体，并在存在和 不存在环氧合酶抑制剂。 条件培养基 将用于培养 在运输分析之前对实质细胞进行分析。 类似 实验将用血清和非- 注射生理盐水的大鼠的实质细胞（对照） 或内毒素。 为了确定外周炎性细胞 浸润有助于细胞因子的制定， 肝脓毒症反应，大鼠将注射 内毒素并在此后的特定时间处死。 的 这些动物的肝脏将被处理， 组织学检查（核心设施）和浸润 与增强型氨基酸相比， 摄取。 如有必要，识别炎性细胞 将通过使用已知的抗体进行浸润， 炎症细胞的表面标记。 从这些 研究将是重要的，因为更好地了解 这种适应性反应将导致改善 营养/激素疗法的目标，以造福 病人

During severe infection, the liver becomes the principle organ of amino acid uptake, an adaptive response which supports acute-phase protein synthesis and confers a survival advantage to the host. Increased hepatic amino acid extraction during sepsis is largely attributable to augmented plasma membrane transport activity. The focus of the proposed research is to examine the role of non- parenchymal liver cells as the source of plasma-borne mediators that trigger increased plasma membrane amino acid uptake in parenchymal cells. We are particularly interested in the amino acid uptake in parenchymal cells. We are particularly interested in the amino acid glutamine because it has been shown to be "conditionally-essential" in some catabolic states, and transport across the plasma membrane may represent a rate-limiting step in its metabolism. Preliminary data from our laboratory indicate that the ability to enhance hepatic glutamine transport is cytokine-mediated and is essential for survival. Isolated rat hepatocytes will be utilized to examine the effects of individual cytokines, hormones, conditioned media from non-parenchymal cells, and serum from endotoxin- treated animals on amino acid transport. To examine the role of inflammatory cytokines/hormones, isolated rat parenchymal cells will be incubated with IL-1, TNF, IL-6, PGE2, and dexamethasone, alone and in combination, followed by assay of glutamine and alanine transport activity. To elucidate the role of sinusoidal cells in the response, non-parenchymal cells (NPC's: Kupffer cells, endothelial cells) will be isolated and cultured L+ endotoxin or TNF- alpha in the presence and absence of neutralizing antibodies to effective cytokines, and in the presence and absence of a cyclooxygenase inhibitor. Conditioned media from these cells will be used for the culture of parenchymal cells prior to transport analysis. Similar experiments will be conducted with serum and non- parenchymal cells from rats injected with saline (control) or endotoxin. To determine if peripheral inflammatory cell infiltrates contribute to cytokine elaboration during the hepatic septic response, rats will be injected with endotoxin and sacrificed at specific times thereafter. The livers from these animals will be processed for histological examination (core facility), and infiltrate appearance compared with that of enhanced amino acid uptake. If necessary, identification of inflammatory cell infiltrates will be performed by use of antibodies to known surface markers on inflammatory cells. Results from these studies will be important because a better understanding of this adaptive response will lead to improved nutritional/hormonal therapies targeted to benefit the patient.