Nitric Oxide Transport By Hemoglobin

血红蛋白转运一氧化氮

• 批准号: 8741366
• 负责人: Alan Schechter
• 金额: $ 42.55万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8741366
• 关键词: Acids; Acute; Affect; Animals; Ascorbic Acid; Binding; Biological; Biological Assay; Blood; Blood Circulation; Blood Clot; Blood Platelets; Blood Pressure; Blood Vessels; Blood coagulation; Blood flow; Breathing; Cardiovascular Diseases; Cardiovascular Pathology; Cells; Chemicals; Chronic; Coagulation Process; Cysteine; Dehydroascorbic Acid; Development; Disease; Drops; Erythrocytes; Exhalation; Free Radicals; Frequencies; Functional disorder; Gases; Heme; Hemoglobin; Hemolytic Anemia; Hormones; Human; Human Volunteers; Hypoxia; In Vitro; Individual; Infusion procedures; Ions; Iron; Lead; Left; Lesion; Link; Measures; Metabolism; Methemoglobin; Methods; Modeling; Molecular Conformation; Newborn Infant; Nitrates; Nitric Oxide; Nitrites; Oxidation-Reduction; Oxygen; Pathology; Patients; Peripheral; Pharmaceutical Preparations; Physiological; Platelet aggregation; Positioning Attribute; Preparation; Process; Production; Property; Proteins; Pulmonary Hypertension; Pulmonary artery structure; Reaction; Reporting; Research; Research Design; Role; S-nitrosohemoglobin; SKIL gene; Sheep; Sickle Cell; Sickle Cell Anemia; Signal Transduction; Site; Source; Surface; Syndrome; System; TNFRSF5 gene; Therapeutic; Tissues; Transfusion; Venous; Work; arm; beta Globin; brachial artery; cardiovascular risk factor; deoxyhemoglobin; falls; human subject; in vivo; instrument; interest; older patient; pressure; programs; research clinical testing; volunteer

The results of nitric oxide (NO) infusions in normal volunteers and NO infusions and inhalation in experimental animals confirms that NO can be transported as a hormone and thus has the potential to be a pharmacological agent (i.e., a drug). We believe that the lack of vascular effects in our sickle cell patients is due to the presence of circulating hemoglobin and that this contributes to the pathophysiology of this and other chronic and acute hemolytic syndromes, especially the pulmonary hypertension complications which we have found to be severe and of high frequency in older patients. In recent studies we have infused nitrite into the brachial arteries of normal human volunteers and have shown that this increases blood flow, suggesting that nitrite could function physiologically as a source of NO and could be used pharmacologically. However, we find that the effects of nitrite infusion, both on vascular properties and on methemoglobin formation, are relatively long lasting and suggest partition of the nitrite into various tissues. We find that in vitro deoxyerythrocytes and nitrite cause aortic ring preparations to dilate, suggesting a mechanism of nitrite activation by deoxyheme proteins. We also find that nitrite inhalation in hypoxic newborn sheep lead to decreased pulmonary artery pressures and exhalation of NO; nitrite infusions in these animals leads to decreases in mean arterial blood pressure. We are currently studying the formation and compartmentalization of nitrite in the blood, in erythrocytes in particular, and whether nitrite levels may be a marker of cardiovascular risk in humans. These studies are designed to allow us to initiate nitrite infusions in normal human subjects and those with a variety of ischemic (including sickle cell anemia) diseases. We have shown that the maximum production of NO from nitrite occurs near the p50 of hemoglobin and is dependent on the allosteric conformation of hemoglobin. We have also developed methods to measure nitrite levels precisely in human blood and have found that most of blood nitrite is contained in the red cells. This reaction may be the major mechanism for the formation of red cell nitrite, which we believe is one of the major storage sites for bioactive NO in the body, and has led us to develop a model of the interaction of the ascorbic acid/dehyroascorbic acid and the NO/nitrite cycles inside the erythrocyte. We believe that the above studies should contribute to our understanding of the role of the human erythrocyte in modulating NO bioactivity, especially via a nitrite intermediate, and also facilitate the development of nitrite as a useful drug for cardiovascular pathology. In recent work we have been investigating changes in NO-related species during red blood cell storage to ascertain whether these contribute to the complications of blood, especially red cell, transfusion know as the "storage lesion." We find, as expected from our previous work that nitrite levels fall rapidly after venisection but then, surprisingly level off at about 1/4 of the initial value for up to 42 days. We find no evidence of other relevant NO changes and are now investigating whether the nitrite changes contribute to red cell-induced pathology and, equally importantly, the mechanism of control and stabilization of red cell nitrite levels. In the last year we have shown that at physiological nitrite concentrations we can generate enough NO to inhibit platelet aggregation; we are now working on the physiological and pharmacological implications of these results, which appear to involve interactions of nitrite with circulating red blood cells and may contribute to physiological and pathophysiological modulation of platelet reactivity in the circulation. We have also shown that the levels of nitrite in platelets during storage in vitro drop slightly and if this is due to NO formation may contribute to keeping the platelets functional for transfusion. In recent months we have been able to show that we can measure the interaction of red cells, nitrite and blood clotting by thrombelastometry, which measures more steps in clotting than platelet aggregation or surface markers alone. Using this new instrument we may be in a position to expand our work on NO production by red cells to clinical evaluation of blood clotting in various physiological and disease states. This work is closely related to that described in our report on potential nitrite therapeutics.

在正常志愿者中的一氧化氮（NO）输注和在实验动物中的NO输注和吸入的结果证实，NO可以作为激素转运，因此具有成为药理学试剂的潜力（即，药物）。我们认为，镰状细胞患者缺乏血管效应是由于循环血红蛋白的存在，这有助于这种和其他慢性和急性溶血综合征的病理生理学，特别是肺动脉高压并发症，我们发现这种并发症在老年患者中严重且频率高。 在最近的研究中，我们将亚硝酸盐注入正常人类志愿者的肱动脉中，并表明这会增加血流量，这表明亚硝酸盐在生理上可以作为NO的来源，并且可以被使用。然而，我们发现，亚硝酸盐输注的影响，无论是对血管特性和高铁血红蛋白的形成，是相对持久的，并建议分区的亚硝酸盐到各种组织。 我们发现体外脱氧红细胞和亚硝酸盐会导致主动脉环制剂扩张，这表明脱氧血红素蛋白激活亚硝酸盐的机制。 我们还发现，亚硝酸盐吸入缺氧新生绵羊导致肺动脉压降低和呼出的NO;亚硝酸盐输注在这些动物中导致平均动脉血压降低。 我们目前正在研究血液中亚硝酸盐的形成和区室化，特别是在红细胞中，以及亚硝酸盐水平是否可能是人类心血管风险的标志。 这些研究旨在使我们能够在正常人受试者和患有各种缺血性（包括镰状细胞贫血）疾病的受试者中开始亚硝酸盐输注。我们已经表明，从亚硝酸盐的NO的最大生产发生在血红蛋白的p50附近，并依赖于血红蛋白的变构构象。我们还开发了精确测量人体血液中亚硝酸盐水平的方法，并发现大部分血液亚硝酸盐包含在红细胞中。 这种反应可能是形成红细胞亚硝酸盐的主要机制，我们认为这是体内生物活性NO的主要储存位点之一，并使我们开发了一个模型的抗坏血酸/dehydroascorbic acid和NO/亚硝酸盐循环内的红细胞的相互作用。 我们相信，上述研究应有助于我们了解的作用，人红细胞在调节NO的生物活性，特别是通过亚硝酸盐中间体，也促进亚硝酸盐作为一个有用的药物，心血管病理学的发展。在最近的工作中，我们一直在研究红细胞储存过程中NO相关物质的变化，以确定这些变化是否有助于血液，特别是红细胞，输血的并发症，称为“储存性病变”。“我们发现，正如我们以前的工作所预期的那样，亚硝酸盐水平在静脉注射后迅速下降，但令人惊讶的是，在长达42天的时间里，亚硝酸盐水平稳定在初始值的1/4左右。我们没有发现其他相关的NO变化的证据，现在正在研究亚硝酸盐的变化是否有助于红细胞诱导的病理学，同样重要的是，红细胞亚硝酸盐水平的控制和稳定的机制。 在过去的一年中，我们已经表明，在生理亚硝酸盐浓度，我们可以产生足够的NO来抑制血小板聚集，我们现在正在研究这些结果的生理和药理学意义，这似乎涉及亚硝酸盐与循环红细胞的相互作用，并可能有助于生理和病理生理调节循环中的血小板反应性。我们还表明，在体外储存期间，血小板中的亚硝酸盐水平略有下降，如果这是由于NO的形成可能有助于保持血小板的输血功能。最近几个月，我们已经能够证明，我们可以通过血栓弹力测定法测量红细胞，亚硝酸盐和凝血的相互作用，该方法比单独测量血小板聚集或表面标记物更多的凝血步骤。 使用这种新仪器，我们可能能够将我们关于红细胞产生NO的工作扩展到各种生理和疾病状态下血液凝固的临床评估。这项工作是密切相关的，在我们的报告中描述的潜在亚硝酸盐治疗。