CARBON MONOXIDE IN NEWBORN CEREBRAL CIRCULATION

新生儿大脑循环中的一氧化碳

• 批准号: 6095935
• 负责人: CHARLES W. LEFFLER
• 金额: $ 31.95万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-08-16 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6095935
• 关键词: brain circulation; carbon monoxide; enzyme activity; enzyme mechanism; enzyme substrate; gene expression; heme oxygenase; hemodynamics; microcirculation; newborn animals; protein localization; respiratory gas level; swine; tissue /cell culture; vascular endothelium; vasodilatation

The gas, carbon monoxide (CO), is produced physiologically by catabolism of heme via heme oxygenase. One of the isoforms of heme oxygenase, HO-2, is expressed in highest concentration in the brain where it resides in neurons, vascular endothelium and smooth muscle. It generates CO from cellular heme. This application is based on preliminary data that suggest carbon monoxide (CO) is an endogenous mediator in the newborn cerebral circulation. These preliminary data include detection of heme oxygenase 2 (HO-2) in the cerebral vasculature, cerebrovascular dilator responses to exogenously applied CO and to heme oxygenase substrate, and measurements of CO production by cerebral microvessels and endothelium. The likelihood that CO will prove to be a physiologically significant intercellular messenger molecule is high. The research proposed is designed to pursue the unifying hypothesis that CO is an integral component of microvascular control in neonatal cerebral circulation. To test this hypothesis, three specific aims will be addressed in newborn pigs, in vivo, and using cells isolated from newborn pigs, in primary culture: 1. Determine the functional significance of CO in regulation of cerebral microvascular tone, 2. Localize and characterize heme oxygenase of the neonatal cerebral vasculature, 3. Investigate mechanisms of CO induced modifications of cerebral microvascular tone. To accomplish these aims, techniques allowing investigation of intact cerebral microcirculation, isolated cerebral microvessels, and primary culture of cells from newborn pigs will be employed. Such research is unique by studying intact cerebral circulation and investigating, at the cellular and molecular levels, the mechanisms responsible for controlling the production of the mediator, CO, and the mechanisms by which CO can affect vascular tone. Cranial windows allow observation of cerebral circulation, collection of cortical periarachnoid fluid, and topical application of agonists, precursors and inhibitors. Levels and cellular distribution of heme oxygenase protein expression as well as enzyme activity and cellular mechanisms for controlling that activity will be examined. The cellular mechanisms by which CO may modify vascular tone will be studied at the level of membrane potential, ion channels, and second messengers. Disorders of the cerebral circulation in the newborn period are major causes of morbidity and mortality and can result in life long disabilities in survivors. Control of cerebrovascular circulation is easily impaired by pathological conditions. Therefore, better understanding of mechanisms of cerebromicrovascular humoral communication in newborns is needed badly.

这种气体，即一氧化碳 (CO)，是由血红素通过血红素加氧酶分解代谢而产生的。 血红素加氧酶同种型之一 HO-2 在大脑中表达浓度最高，存在于神经元、血管内皮和平滑肌中。 它从细胞血红素产生二氧化碳。 该应用基于初步数据，表明一氧化碳 (CO) 是新生儿脑循环中的内源性介质。 这些初步数据包括脑血管系统中血红素加氧酶 2 (HO-2) 的检测、脑血管扩张器对外源施加的 CO 和血红素加氧酶底物的反应，以及脑微血管和内皮细胞产生的 CO 的测量。 CO 被证明是具有生理意义的细胞间信使分子的可能性很高。 这项研究旨在追求一个统一的假设，即二氧化碳是新生儿脑循环微血管控制的一个组成部分。 为了检验这一假设，将在新生猪体内并使用从新生猪分离的细胞进行原代培养来解决三个具体目标：1.确定CO在调节脑微血管张力中的功能意义，2.定位和表征新生儿脑血管系统的血红素氧合酶，3。研究CO诱导脑微血管张力改变的机制。 为了实现这些目标，将采用能够研究完整脑微循环、分离脑微血管和新生猪细胞原代培养的技术。 此类研究的独特之处在于，它研究了完整的脑循环，并在细胞和分子水平上研究了控制介质 CO 产生的机制，以及 CO 影响血管张力的机制。 颅窗可以观察脑循环、皮质蛛网膜周围液体的收集以及激动剂、前体和抑制剂的局部应用。 将检查血红素加氧酶蛋白表达的水平和细胞分布以及酶活性和控制该活性的细胞机制。 CO 改变血管张力的细胞机制将在膜电位、离子通道和第二信使水平上进行研究。 新生儿期脑循环障碍是发病和死亡的主要原因，并可能导致幸存者终身残疾。 脑血管循环的控制很容易受到病理状况的损害。 因此，迫切需要更好地了解新生儿脑微血管体液通讯的机制。