HISTAMINE METABOLISM IN PULMONARY VASCULAR CELLS

组胺通过直接引起血管收缩而发挥其血管生物学活性 受体介导的血管收缩或血管舒张， 触发脂质介质的产生。 后续 这种激动剂的清除机制似乎在 肺循环与体循环。 该项目旨在定义 组胺的酶机制的性质 受体介导的内吞作用在代谢中的作用 组胺的降解过程，以及这些元素的影响 组胺受体调节，在人内皮细胞 与来自肺血管的细胞相比， 体循环 它将在组织培养中 模型系统的手段，这些细胞和组胺 相互交流，共同探索， 内皮下其他类型细胞的组胺代谢 血管和间质结缔组织的结构- 平滑肌细胞、成纤维细胞和宿主防御细胞 系统，如粒细胞，代表肺和 体循环血管床 目标是确定如何 人肺内皮细胞代谢组胺， 定义在已建立的环中已知哪些类型的酶 甲基化/胺氧化或直接侧链氧化 在各种环境条件下使用路径， 表征代谢酶在以下条件下的潜在相互作用： 内皮细胞表面和内吞作用的参与 组织胺的细胞吸收过程。 代谢产物 将通过薄层色谱法鉴别3 H-组胺， 离子交换层析 组胺的细胞定位 转换和组胺代谢酶将被描绘 在细胞裂解和蔗糖或Percoll 密度梯度离心法 潜在结合和细胞 催化代谢步骤的酶的表面活性将是 在一个类似的人类系统中检测。 我们提供了 有证据表明，组胺代谢在培养的人类系统 血管内皮细胞发生在细胞表面相关的 方式作为一个两阶段的序列，涉及一个初始的降解 通过内源性酶分步，随后通过 外源酶 细胞摄取过程与 酶降解途径。 这个提议是细胞生物学的 生物胺代谢的方法将寻求定义在 细胞水平的机械基础的排斥， 肺循环中组胺的清除。

Histamine exerts its vascular biologic activity by causing direct receptor-mediated vasoconstriction or vasodilation and by triggering the production of lipid mediators. Subsequent clearance mechanisms for this agonist appear to differ in the pulmonary vs. systemic circulation. This project seeks to define the nature of the enzymatic mechanisms for histamine metabolism, the role of receptor-mediated endocytosis in the histamine degradation process, and the impact of these elements on histamine receptor regulation, in human endothelial cells derived from the pulmonary vasculature compared with cells from the systemic circulation. It will characterize in a tissue culture model system the means by which these cells and histamine mutually interact with one another, and explore the participation in histamine metabolism by other cell types in the subendothelial structure of blood vessels and interstitial connective tissue - smooth muscle cells, fibroblasts, and cells of the host defense system such as granulocytes, representing both the pulmonary and systemic vascular beds. The objectives are to determine how human pulmonary endothelial cells metabolize histamine, to define which types of enzymes known in the established ring methylation/amine oxidation or direct side-chain oxidation pathways are utilized under various environmental situations, and to characterize potential interaction of metabolizing enzymes at the endothelial cell surface and involvement of an endocytic process in cellular uptake of histamine. Metabolic products of 3H-histamine will be identified by thin layer chromatography and ion exchange chromatography. The cellular locations of histamine conversion and histamine-metabolizing enzymes will be delineated in subcellular compartments after cell lysis and sucrose or Percoll density gradient centrifugation. Potential binding and cell surface activity of enzymes catalyzing the metabolic steps will be examined in a homologous human system. We have provided evidence that histamine metabolism in cultured human systemic vascular endothelial cells takes place in a cell-surface-associated manner as a two-stage sequence, involving an initial degradative step by an endogenous enzyme and a subsequent one by an exogenous enzyme. A cellular uptake process is tightly coupled to the enzymatic degradation pathway. This proposal's cell biologic approach to biogenic amine metabolism will seek to define at the cellular level the mechanistic basis for the exclusion of the pulmonary circulation in histamine clearance.