Nitric Oxide Transport Mechanisms: Model and Experiments

描述（申请人提供）：拟议研究的总体目标是提高我们对血液和组织中一氧化氮（NO）、血红蛋白、氧气、二氧化碳和硫醇之间复杂相互作用的理解。近年来，关于血液中NO的产生和运输以及可能影响这些过程的各种因素，提出了许多假设。然而，对于NO的作用和转运的真正机制仍然存在分歧。几个具体的问题仍然存在（1）细胞内钙、氧、剪切应力和巯基水平的复杂相互作用如何影响内皮产生并递送到组织的NO的量？(2)亚硝基硫醇或亚硝基血红蛋白（SNO-I-Ib）是否作为一种易化载体机制，通过储存NO并将其运输到需要的区域？(3)数学模型能帮助确定NO最可能的传输机制吗？拟议的研究旨在回答这些问题，使用在体外和体内的实验研究和数学建模的组合实验研究已被设计为提供重要的信息的数学建模，并将用于测试模型的有效性和评估假设的机制NO运输在体外研究将进行在平行板流动室使用大鼠内皮细胞。一氧化氮释放将使用神经体液介质刺激，并在基础条件下测量。将施加额外的条件，包括改变的氧气和二氧化碳水平、各种水平的剪切应力和添加硫醇。将在大鼠肠系膜的小动脉和小静脉中进行体内研究。将在正常生理条件下、在缺氧和高碳酸血症期间以及在改变的硫醇、剪切应力和血细胞比容水平下测量NO水平。这些干预措施对NO的产生，运输和分布的影响将被测量，纳入数学模型，并用于在各种条件下测试其有效性。该数学模型将模拟NO在微循环和组织中的产生、质量运输、反馈调节和生化作用机制。从验证模型中获得的定量数据将用于预测无法在体内测量的参数，分析假设并进一步了解NO的产生和运输机制，并用于塑造未来的实验研究。了解NO转运机制在临床上是重要的，因为NO调节的改变与病理生理条件有关

DESCRIPTION (provided by applicant): The general goal of the proposed research is to improve our understanding of the complex interaction between nitric oxide (NO), hemoglobin, oxygen, carbon dioxide, and thiols in the blood and tissue In recent years, many hypotheses have been suggested regarding the production and transport of NO in the blood and various factors that may affect these processes However, disagreement still exists over the true mechanisms of action and transport of NO. Several specific questions remain (1) How do the complex interactions of intracellular calcium, oxygen, shear stress, and thiol levels affect the amount of NO produced by the endothelium and delivered to tissue? (2) Do nitrosothiols or nitrosylhemoglobin (SNO-I-Ib) act as a facilitated carrier mechanism by storing NO and transporting it to areas where it is needed? (3) Can mathematical modeling assist in determining the most probable transport mechanisms for NO? The proposed research seeks to answer these questions using a combination of in vitro and in vivo experimental studies and mathematical modeling Experimental studies have been designed to provide vital information for the mathematical modeling and will be used to test model validity and evaluate hypothesized mechanisms of NO transport In vitro studies will be conducted in a parallel-plate flow chamber using rat endothelial cells. Nitric oxide release will be stimulated using neurohumoral mediators and measured under basal conditions. Additional conditions, including altered oxygen and carbon dioxide levels, various levels of shear stress and addition of thiols will be imposed. In vivo studies will be conducted in the arterioles and venules of the rat mesentery. NO levels will be measured under normal physiological conditions, during hypoxia and hypercapnia and under altered thiol, shear stress and hematocrit levels. The effects of these interventions on NO production, transport, and distribution will be measured, incorporated into the mathematical model, and used to test its validity under various ranges of conditions. The mathematical model will simulate the production, mass transport, feedback regulation, and biochemical mechanisms of action of NO in the microcirculation and tissue. Quantitative data obtained from the validated model will be used to predict parameters that cannot be measured in vivo, analyze the hypotheses and further the understanding of NO production and transport mechanisms, and used to shape future experimental studies. Understanding NO transport mechanisms is important clinically since altered NO regulation has been implicated in pathophysiological conditions