REDOX ACTIVITY OF THE PULMONARY ENDOTHELIAL SURFACE

肺内皮表面的氧化还原活性

• 批准号: 6527062
• 负责人: MARILYN P MERKER
• 金额: $ 18.9万
• 依托单位: MEDICAL COLLEGE OF WISCONSIN
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-20 至 2004-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6527062
• 关键词: antioxidants; blood lipoprotein metabolism; cell membrane; electron transport; human tissue; membrane proteins; oxidation reduction reaction; oxidative stress; paraquat; pulmonary circulation; pyridine nucleotide; toxin metabolism; ubiquinone; vascular endothelium

Transplasma membrane electron transport (TPMET) systems in pulmonary endothelial cells effect reduction of extracellular electron acceptors via transport of intracellular donors to the extracellular acceptors. The physiological role and mechanisms of pulmonary TPMET are not well understood. A general hypothesis motivating the proposed research is that pulmonary endothelial TPMET influences the redox status of systemic arterial blood constituents. This function can have either antioxidant or prooxidant consequences depending on the nature of the electron acceptors arriving via the mixed venous blood. In its antioxidant role, pulmonary endothelial TPMET regeneration of plasma lipoprotein antioxidants contributes to antioxidant defense of the systemic circulation. This is, in part, a functional outcome of the large pulmomary endothelial surface area and the location of the lung in the circulatory system. The very properties of lung TPMET that promote its protective effects also have the potential to initiate oxidant injury when TPMET systems are presented with redox active toxins or free transition metal electron acceptors. The goal of the proposed studies is to examine these concepts and to further elucidate cellular mechanisms involved in pulmonary endothelial TPMET. The specific aims of the proposed research are as follows: I. Determine the influence of pulmonary endothelial TPMET on the extracellular redox state of physiological or toxicological redox active compounds. The specific hypotheses are that pulmonary endothelial TPMET systems (1) reduce the oxidized form of coenzyme Q0 and Trolox C quinone to their antioxidant hydroquinone forms, (2) regenerate the reduced forms of the plasma lipoprotein antioxidant coenzyme Q10 as a mechanism underlying endothelial protection of plasma lipoprotein from oxidation, and 3) reduce the pulmonary toxin paraquat to its prooxidant monocation form. The general approach will be to demonstrate that reduction products of these electron acceptors appear in the extracellular medium when the intact cells are exposed to the oxidized forms, and to determine whether there are proteins on the cell surface that are capable of mediating the reduction carried out by the intact cells. II. Elucidate cellular mechanisms involved in TPMET. The specific hypotheses are that the activity of one of the pulmonary endothelial TPMET systems (1) depends on intracellular redox status as reflected in the intracellular NAD(P)H/NAD(P)+ ratios, and (2) involves a TPMET flavoprotein, and possibly other, redox centers. The general approach will be to correlate TPMET activity and pyridine nucleotide redox poise in intact cells and to determine some of the effects of redox prosthetic group inhibitors on the reductase activity of isolated plasma membrane redox components.

肺内皮细胞中的跨质膜电子传递（TPMET）系统通过将细胞内供体转运至细胞外受体来实现细胞外电子受体的减少。 肺TPMET的生理作用和机制尚未完全了解。 一个普遍的假设，激励拟议的研究是，肺内皮TPMET影响全身动脉血液成分的氧化还原状态。 这种功能可以具有抗氧化或促氧化的后果，这取决于通过混合静脉血到达的电子受体的性质。 在其抗氧化作用中，肺内皮TPMET再生血浆脂蛋白抗氧化剂有助于体循环的抗氧化防御。 这在一定程度上是肺动脉内皮表面积大和肺在循环系统中的位置的功能结果。 当TPMET系统与氧化还原活性毒素或游离过渡金属电子受体一起存在时，肺TPMET促进其保护作用的特性也具有引发氧化损伤的潜力。 提出的研究的目标是检查这些概念，并进一步阐明参与肺内皮TPMET的细胞机制。 本研究的具体目标如下：一、研究目的：确定肺内皮TPMET对生理或毒理学氧化还原活性化合物的细胞外氧化还原状态的影响。 具体的假设是，肺内皮TPMET系统（1）将辅酶Q 0和Trolox C醌的氧化形式还原为它们的抗氧化剂氢醌形式，（2）再生血浆脂蛋白抗氧化剂辅酶Q10的还原形式，作为内皮保护血浆脂蛋白免受氧化的潜在机制，和3）将肺毒素百草枯还原为其促氧化剂单价阳离子形式。 一般的方法是证明当完整细胞暴露于氧化形式时，这些电子受体的还原产物出现在细胞外介质中，并确定细胞表面上是否存在能够介导完整细胞进行的还原的蛋白质。 二.阐明TPMET中涉及的细胞机制。 具体的假设是，肺内皮TPMET系统之一的活性（1）取决于细胞内NAD（P）H/NAD（P）+比率所反映的细胞内氧化还原状态，和（2）涉及TPMET黄素蛋白，以及可能的其他氧化还原中心。 一般的方法是将TPMET活性和完整细胞中的吡啶核苷酸氧化还原平衡相关联，并确定氧化还原辅基抑制剂对分离的质膜氧化还原组分的还原酶活性的一些影响。