HEPATIC AMINO ACID TRANSPORT DURING SERIOUS INFECTION

在严重感染期间，肝脏成为主要 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 对宿主的生存优势。肝氨酸量增加 脓毒症期间的酸提取主要归因于 增强质膜转运活性。的关注点 这项拟议的研究是为了检查非 肝实质细胞作为血浆来源的研究进展 引发质膜氨基酸增加的介质 实质细胞的摄取。我们特别是 对实质细胞中的氨基酸摄取感兴趣。 我们对氨基酸谷氨酰胺特别感兴趣 因为它已经被证明是“有条件的必要的” 在某些分解代谢状态下，并通过血浆运输 膜可以代表其速率限制步骤 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是 由细胞因子介导，是生存所必需的。 分离的大鼠肝细胞将被用于检测 个别细胞因子、激素、条件作用的影响 培养液来自非实质细胞，血清来自内毒素- 用氨基酸转运治疗的动物。要检查 炎性细胞因子/激素在隔离大鼠体内的作用 实质细胞与IL-1、TNF、IL-6共同孵育， PGE2和地塞米松单独和联合使用紧随其后 测定谷氨酰胺和丙氨酸转运活性。至 阐明正弦细胞在反应中的作用， 非实质细胞(NPC：Kupffer细胞、内皮细胞 细胞)分离培养L+内毒素或肿瘤坏死因子- 存在和不存在中和的阿尔法 有效细胞因子的抗体，并且在存在和 没有环氧合酶抑制剂。条件培养液 这些细胞将被用于培养 运输分析前的实质细胞。类似 实验将用血清和非 注射生理盐水大鼠的实质细胞(对照组) 或者是内毒素。以确定外周炎性细胞 浸润物在细胞因子的形成过程中起作用 肝脓毒症反应，大鼠将注射 内毒素，然后在特定时间处死。这个 这些动物的肝脏将被加工成 组织学检查(核心设施)和浸润性 外观与强化氨基酸的比较 领悟。如有必要，对炎症细胞进行鉴定 通过使用已知的抗体进行渗透 炎性细胞表面标志物。来自这些的结果 研究将是重要的，因为更好地理解 这种适应性反应将带来改进 营养/激素疗法的目标是使 有耐心的。

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.