HISTAMINE METABOLISM IN HUMAN PULMONARY VASCULAR CELLS

发生在人肺中的病理过程通常涉及肺内的炎症。 肺内皮细胞损伤的组成部分或这些反应 细胞局部释放介质。 由于其内容丰富， 肥大细胞和肺血管床的范围，肺是两者都是 丰富的组胺来源和一个潜在的重要性， 通过与脉管系统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血管舒张，并通过触发 产生洋地黄素、白三烯和羟基脂肪酸。 两 血管张力的变化和炎症介质的释放可能 在肺部疾病或损伤的进展中发挥作用。 这个项目 将探索组胺的酶机制的性质 存在于肺血管系统的培养的人细胞中的代谢 与来自体循环的细胞相比。 其目标是 确定人肺内皮细胞如何代谢组胺， 定义哪些酶在已建立的环甲基化/胺氧化或 存在直接侧链氧化途径，并表征 内皮细胞代谢酶的潜在相互作用 表面和参与细胞摄取的内吞过程 组胺。 3 H组胺在内皮细胞中的代谢产物， 乙酸：乙醇提取和薄层色谱法鉴别 在区分由甲基化产生的代谢物的溶剂系统中， 相对于氧化。 组胺转化的细胞位置将是 通过测量亚细胞中总3 H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， 通过薄层扫描法测定标记产物的化学性质， 层析 酶的潜在结合和细胞表面活性 催化氧化步骤将在人类肺部进行检查 内皮细胞通过测量细胞相关的放射性， 异源胎牛125 I-二胺氧化酶和通过鉴定3 H 在其存在下产生的组胺代谢物。 的参与 人肺血管平滑肌细胞组胺代谢将 还可通过酶和3 H组胺的鉴定来表征 代谢产物 代谢酶，可能会被释放， 与细胞损伤的相关性最终可用作 表示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.