NMR STUDIES OF ISCHEMIC INJURY IN THE PERFUSED HEART

核磁共振波谱的独特诊断和非侵入性优势将 用于研究跨动脉膜阳离子的调节 缺血和再灌注期间的梯度及其在细胞损伤中的作用 和恢复。 细胞内 Na+将使用最近的23 Na NMR连续监测 研制了~（23）Na核磁共振位移试剂Tm（DOTP）~（5-）。 这种独特的试剂不仅 提供了细胞内Na+共振的优异分辨率，但 与高质量31 P光谱的采集兼容。 利用 其中，一个专门设计的核磁共振探针将用于收集交错的 相同制备物的23 Na和31 P NMR光谱。 高能磷酸 并且将从31 P NMR光谱监测细胞内和细胞外pH， 利用无机磷酸盐和苯基磷酸盐的化学位移， 细胞外pH标志物。 此外，细胞内游离Ca 2+将被 通过使用加载氟化Ca 2+指示剂，5 F-19 F NMR测量 BAPTA。 这些方法最终将结合起来; Na+和Ca 2+将 首次在同一制剂中通过NMR测定。 的 该项目的具体目标是确定改变 缺血和再灌注期间肌膜Na+和Ca 2+梯度，以及 以确定这两个梯度是如何耦合在一起的， 能源供应。 阳离子稳态与功能恢复的关系 将被调查。 糖酵解能量产生的重要性 在缺血和再灌注期间维持阳离子梯度将是 研究了 将采用两种不同的缺血模型，均为低- 血流和零血流全脑缺血。 Na+/H+交换的作用 通过使用特异性抑制剂直接研究 乙基异丙氨氯吡。 这些问题将在 高血压动物模型，自发性高血压大鼠，使用年龄- 匹配的Wistar-Kyoto大鼠作为对照，以研究 肥大的心脏到局部缺血 Ca ~（2+）作为一种介体的作用 可以阐明细胞损伤，从而更好地了解 关于可能的治疗的心肌缺血。

The uniquely diagnostic and noninvasive advantages of NMR spectroscopy will be employed to investigate the regulation of transarcolemmal cation gradients during ischemia and reperfusion, and their role in cell damage and recovery, in the perfused isovolumic rate heart model. Intracellular Na+ will be continuously monitored with 23Na NMR using the recently developed 23Na NMR shift reagent Tm(DOTP)5-. This unique reagent not only provides excellent resolution of the intracellular Na+ resonance, but is compatible with acquisition of high quality 31P spectra. Taking advantage of this, a specially designed NMR probe will be used to collect interleaved 23Na and 31P NMR spectra on the same preparation. High energy phosphates and intra- and extracellular pH will be monitored from the 31P NMR spectra, using the chemical shifts of inorganic phosphate and phenylphosphate, an extracellular pH marker. Additionally, free intracellular Ca2+ will be measured with 19F NMR by using loading the fluorinated Ca2+ indicator, 5F- BAPTA. These methodologies will ultimately be combined; Na+ and Ca2+ will be measured in the same preparation for the first time by NMR. The specific aims of this project are to determine the mechanisms which alter the sarcolemmal Na+ and Ca2+ gradients during ischemia and reperfusion, and to determine how these two gradients are coupled together, and to the energy supply. The relation of cation homeostasis to functional recovery will be investigated. The importance of glycolytic energy production in maintaining cation gradients during ischemia and reperfusion will be investigated. Two different models of ischemia will be employed, both low- flow and zero-flow global ischemia. The role of Na+/H+ exchange will investigated directly by using the specific inhibitor ethylisopropylamiloride. These issues will be addressed in the hypertensive animal model, the Spontaneously Hypertensive Rat, using age- matched Wistar-Kyoto rats as controls, to investigate the sensitivity of the hypertrophied heart to ischemia. The role of Ca2+ as a mediator of cell damage could be elucidated, leading to a better understanding of myocardial ischemia with regard to possible treatments.