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NMR结合使用的分离的心肌细胞模型 光谱学连续探测真实的时间之间的相互作用 代谢和离子转运。 我们已经做了初步的研究， 监测高能代谢物，结合Na NMR监测 钠转运 初步数据表明，离散源和/或 细胞能量的位置（细胞膜与细胞质）对细胞的生长至关重要。 维持肌细胞钠梯度， 这种功能在不同的疾病模型（自发性高血压 (SH)、糖尿病（DM）和慢性高脂血症（HPL）比较 控制。 我们建议利用 Na转运抑制剂（Na，K-ATP酶抑制剂，如哇巴因）， 和能量学的特异性抑制剂（2-脱氧葡萄糖或碘乙酸， 阻断糖酵解，寡霉素阻断氧化磷酸化，和 二硝基苯酚以解偶联氧化磷酸化）。 具体问题是：1）支持Na转运的比例是多少 糖酵解与氧化过程，在常氧或缺血？ 2)如何钠运输和生物能量学相关的这些改变， 疾病状态？3)钠转运蛋白的改变是 特定的病理生理事件？4)钠磷核磁共振能用来定义 这些过程？ 为了进一步使用该模型研究临床相关问题， 将进行另外的研究以评估肌细胞的作用（如 与内皮细胞、平滑肌细胞和白色血细胞相反）， 预处理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 本质上与预处理保护有关。 较小 在长时间缺血期间Nai的增加稳定了膜 电位，降低Na+和Ca 2+交换，从而降低Ca 2 + 超载。 此外，假设保护作用也是 与维持糖酵解功能有关 缺血 这两个过程都将用Na和 P NMR。 该项目的目标有两个：1）证明，具体 钠转运异常是心脏病的重要决定因素， 病理生理学; 2）探索使用核磁共振技术作为诊断 评估病理生理过程的工具，具有适应性“眼睛” 这些技术用于临床。 这些研究将允许描绘的机制和能量 钠转运，这将允许表征疾病过程。 来自对照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.