SODIUM TRANSPORT IN DISEASES CARDIOMYOCYTES--A NMR STUDY

为了确定心脏细胞的生化功能，我们开发了一种 可与核磁共振联合使用的分离心肌细胞模型 光谱学不断探测实时相互作用 新陈代谢和离子运输。我们已经用P核磁共振进行了初步研究 监测能量代谢产物结合核磁共振监测 钠的运输。初步数据表明，离散来源和/或 细胞能量的位置(膜与细胞质)对 维持心肌细胞的钠梯度，并存在差异 这种功能在不同的疾病模型(自发性高血压)中起作用 (SH)、糖尿病(DM)和慢性高脂血症(HPL)的比较 到控制程序。我们建议通过使用以下方法进一步探讨这些机制 钠转运抑制剂(Na，K-ATPase抑制剂，如哇巴因)， 和能量学的特定抑制剂(2-脱氧葡萄糖或碘乙酸酯 阻断糖酵解，寡霉素阻断氧化磷酸化，以及 二硝基苯酚去偶联氧化磷酸化)单独和组合。 具体问题是：1)支持钠转运的比例是多少 在常氧或缺血期间，通过糖酵解和氧化过程？ 2)钠转运和生物能量学的相关性是如何改变的 疾病状态？3)钠转运蛋白改变的基础 特定的病理生理事件？4)钠和P核磁共振能用来确定 这些过程？ 为了进一步利用这一模型来研究临床相关问题， 将进行更多的研究来评估心肌细胞(AS)的作用 与血管内皮细胞、平滑肌和白细胞相对) 预适应对长时间缺血的保护作用。它 假设长时间维持钠、钾转运功能 本质上参与了预适应保护。小点 在长时间的缺血期间NaI的增加稳定了细胞膜 潜在和减少钠和钙的交换，从而降低钙 超载。此外，还假设保护作用也是 与糖酵解功能在延长期间和之后维持有关 缺血症。这两个过程都将用钠和钠联合监测 P-核磁共振。 这个项目目标有两个：1)展示具体的 钠转运异常是心脏疾病的重要决定因素 病理生理学；2)探索使用核磁共振技术作为诊断 一种评估病理生理过程的工具，用一只“眼睛”来适应 这些临床使用的技术。 这些研究将使我们能够描绘出 NA运输，这将使疾病过程得以表征。 对照组大鼠和心血管疾病动物模型的心肌细胞 (DM、SH、HPL)将在基线条件下和 抑制特定的运输和代谢过程。

To define biochemical function in hearts cells, we have developed an isolated cardiomyocyte model which can be used in conjunction with NMR spectroscopy to continuously probe the interaction between real time metabolism and ion transport. We have done initial studies using P NMR to monitor energetic metabolites in conjunction with Na NMR to monitor sodium transport. Preliminary data suggest that discrete source and/or location (membrane vs cytoplasm) of cellular energy are critical to the maintenance of myocyte Na- gradients and that there are differences in this function in different models of disease (spontaneous hypertension (SH), diabetes mellitus (DM) and chronic hyperlipidemia (HPL) compared to controls. We proposed to further explore these mechanism by using inhibitors of Na transport (Na, K-ATPase inhibitors, such as ouabain), and specific inhibitors of energetics (2-deoxyglucose or iodoacetate to block glycolysis, oligomycin to block oxidative phosphorylation, and dinitrophenol to uncouple oxidative phosphorylation) alone and combined. Specific questions are: 1) What proportion of Na transport is supported by glycolytic versus oxidative processes, during normoxia or ischemia? 2) How are Na transport and bioenergetics correlates of these altered by disease states? 3) Are altered Na transporter processes the basis of specific pathophysiologic events? 4) Can Na ad P NMR be used to define these processes? To further use this model to investigate clinically relevant problems, additional studies will be done to evaluate the role of the myocyte (as opposed to endothelial, smooth muscle, and white blood cells) in preconditioning protection against the effect of prolonged ischemia. It is hypothesized that prolonged maintenance of Na,K, transport function is intrinsically involved in the preconditioning protection. Smaller increases in Nai during prolonged ischemia stabilized the membrane potential and decrease Na+ and Ca2+ exchange, thereby decreasing Ca2+ overload. Further, it is hypothesized that the protective effect is also related to maintenance of glycolytic function during and after prolonged ischemia. Both of these processes will be monitored with combined Na and P NMR. The goal of this project are two: 1) to demonstrate that specific abnormalities in Na transport are important determinants of cardiac pathophysiology; 2) to explore the use of NMR techniques as a diagnostic tool to evaluate pathophysiological processes with an "eye" to adapt these techniques for clinical use. These studies will allow delineation of the mechanisms and energetics of Na transport which will allow characterization of disease processes. Myocytes from controls rats and animal models of cardiovascular disease (DM, SH, HPL) will be studied under baseline conditions and during inhibition of specific transport and metabolic processes.