HISTAMINE METABOLISM IN PULMONARY VASCULAR CELLS

组胺通过直接引起血管生物活性而发挥其血管生物活性。 受体介导的血管收缩或扩张，并通过 从而触发脂质介体的产生。后续 这种激动剂的清除机制似乎不同于 肺循环与体循环的对比。这个项目试图定义 组胺的酶作用机制的本质 新陈代谢，受体介导的内吞作用在 组胺的降解过程，以及这些因素的影响 关于人内皮细胞组胺受体调节的研究 来自肺血管系统的细胞与来自于 体循环。它将在组织培养中表现为 模型系统这些细胞和组胺的方式 相互互动，探索参与 内皮下其他类型细胞在组胺代谢中的作用 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 全身血管床。目标是确定如何 人肺内皮细胞代谢组胺，以 确定已建立的环中已知的酶的类型 甲基化/胺氧化或直接侧链氧化 路径在不同的环境情况下使用，并且 为了表征代谢酶的潜在相互作用， 内皮细胞表面和内皮细胞的参与 细胞摄取组胺的过程。新陈代谢产物 ~3H-组胺将通过薄层层析和 离子交换层析。组胺的细胞定位 将描述转化和组胺代谢酶 在细胞裂解和蔗糖或Percoll后的亚细胞室中 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 在一个同源的人类系统中进行检查。我们已经提供了 组胺代谢在培养的人全身系统中的证据 血管内皮细胞发生在一种与细胞表面相关的 作为两个阶段的序列，涉及初始降解物 通过一种内源酶，然后通过一种 外源酶。细胞摄取过程与 酶降解途径。这项提议的细胞生物学 生物胺代谢的方法将寻求在 在细胞水平上，排除了 组胺清除中的肺循环。

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.