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了解。近年来，关于NO在血液中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说，但对于NO的真正作用和运输机制仍存在分歧。仍然有几个具体的问题：(1)细胞内钙、氧、剪切力和硫醇水平的复杂相互作用如何影响内皮细胞产生并输送到组织中的NO的量？(2)亚硝硫醇或亚硝基血红蛋白(SNO-I-Ib)是否通过储存NO并将其输送到需要的区域而起到促进载体机制的作用？(3)数学建模是否有助于确定NO最可能的运输机制？这项拟议的研究试图利用体外和体内实验研究和数学建模相结合的方法来回答这些问题。实验研究旨在为数学建模提供重要信息，并将用于测试模型的有效性和评估假设的NO转运机制。体外研究将在平行平板流室中进行，使用大鼠内皮细胞。一氧化氮的释放将被神经体液介质刺激，并在基础条件下进行测量。其他条件，包括改变氧气和二氧化碳水平，不同水平的剪应力和添加硫醇将被施加。体内研究将在大鼠肠系膜的小动脉和小静脉中进行。在正常生理条件下，在低氧和高碳酸血症期间，以及在改变的硫醇、切应力和红细胞压积水平下，将测量NO水平。这些干预措施对NO生产、运输和分配的影响将被测量，并被纳入数学模型，并用于测试其在各种条件下的有效性。该数学模型将模拟NO在微循环和组织中的产生、质量传输、反馈调节和生化作用机制。从经过验证的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，分析假说并进一步了解NO的产生和传输机制，并用于塑造未来的实验研究。了解NO转运机制在临床上很重要，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