HISTAMINE METABOLISM IN HUMAN PULMONARY VASCULAR CELLS

发生在人类肺部的病理过程通常涉及一种 肺内皮细胞损伤的成分或对这些成分的反应 细胞到局部释放的介体。因为它的主要内容是 肥大细胞和肺血管床的范围，肺都是 丰富的组胺来源和一个潜在的重要部位 通过与血管细胞的相互作用清除组胺。 组胺通过引起H1和/或H2在肺中发挥其生物活性 受体介导的血管收缩或扩张，并通过触发 生产前列腺素、白三烯和羟基脂肪酸。两者都有 血管张力和炎症介质释放的变化可能 在肺部疾病或损伤的进展中起作用。这个项目 将探索组胺的酶机制的本质 培养的人肺血管细胞的代谢 与来自体循环的细胞相比。目标是 确定人肺内皮细胞如何代谢组胺，以 定义已建立的环甲基化/胺氧化中的哪些酶 存在直接侧链氧化途径，并表征 代谢酶在内皮细胞中的潜在相互作用 内吞过程在细胞摄取中的表面和参与 组胺。内皮细胞中组胺的代谢产物将是 乙酸法鉴定：乙醇提取和薄层层析 在区分甲基化产生的代谢物的溶剂体系中 而不是氧化。组胺转化的细胞位置将是 通过测量亚细胞内总的~3H组胺放射性来描绘 细胞裂解和蔗糖密度梯度离心后的隔室， 通过薄层分析确定标示产品的化学性质 层析法。酶的潜在结合力和细胞表面活性 催化氧化的步骤将在人类肺脏中进行检测 通过测量血管内皮细胞的细胞相关放射性 异源胎牛~(125)I-二胺氧化酶及其~3H鉴定 在它的存在下产生的组胺代谢物。中国政府的参与 组胺代谢中的人肺血管平滑肌细胞 也具有鉴定酶和~3H组胺的特征 代谢产物。可能在体内释放的代谢酶 与细胞损伤的关联最终可能是有用的标记 表示活体内人肺内皮细胞损伤。

Pathologic processes occurring in the human lung commonly involve a component of injury to pulmonary endothelial cells or the response of these cells to locally released mediators. Because of its substantial content of mast cells and the scope of the pulmonary vascular bed, the lung is both is rich source of histamine and a locus of potential importance for the clearance of histamine via interaction with cells of the vasculature. Histamine exerts its biologic activity in the lung by causing H1 and/or H2 receptor-mediated vasoconstriction or vasodilation and by triggering the production of prostaglandins, leukotrienes, and hydroxy fatty acids. Both the changes in vascular tone and the release of inflammatory mediators may play a role in the progression of lung disease or injury. This project will explore the nature of the enzymatic mechanisms for histamine metabolism present in cultured human cells of the pulmonary vasculature compared with cells from the systemic circulation. The objectives are to determine how human pulmonary endothelial cells metabolize histamine, to define which enzymes in the established ring methylation/amine oxidation or direct side-chain oxidation pathways are present, 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 in endothelial cells will be identified by acetic acid: ethanol extraction and thin layer chromatography in solvent systems which distinguish metabolites arising from methylation versus oxidation. The cellular locations of histamine conversion will be delineated by measuring total 3H histamine radioactivity in subcellular compartments after cell lysis and sucrose density gradient centrifugation, and determining the chemical nature of the labeled products by thin-layer chromatography. Potential binding and cell surface activity of enzymes catalyzing the oxidation step will be examined in human pulmonary endothelial cells by measuring cell-associated radioactivity of a heterologous fetal bovine 125I-diamine oxidase and by identifying 3H histamine metabolites generated in its presence. The participation of human pulmonary vascular smooth muscle cells in histamine metabolism will also be characterized by identification pf enzymes and 3H histamine metabolic products. Metabolizing enzymes which may be released in association with cellular injury may ultimately be useful as markers for denoting human pulmonary endothelial cell injury in vivo.