NMR STUDIES OF ISCHEMIC INJURY IN THE PERFUSED HEART

核磁共振光谱学独特的诊断和非侵入性优势将 被用来研究跨膜阳离子的调节 缺血和再灌注过程中的梯度及其在细胞损伤中的作用 在灌流等容率心脏模型中，恢复。细胞内 将使用最近的23Na核磁共振连续监测Na+ 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 提供了出色的细胞内Na+共振分辨率，但 兼容高质量31P光谱的获取。利用 其中，一个特别设计的核磁共振探测器将被用来收集交错的 同一制剂的~(23)Na和~(31)P核磁共振波谱。高能磷酸盐 细胞内外的pH值将从31P核磁共振谱中监测出来， 利用无机磷酸盐和苯基磷酸盐的化学位移， 胞外pH标记物。此外，细胞内游离钙离子将被 用~(19)F-核磁共振法测定~(19)F-Ca~(2+)的含量 BAPTA。这些方法最终将合并；Na+和Ca~(2+)将 首次在同一制剂中用核磁共振进行测定。这个 这个项目的具体目标是确定改变 缺血再灌流时心肌细胞膜Na+和Ca~(2+)浓度的变化 要确定这两个渐变如何耦合在一起，以及 能源供应。阳离子动态平衡与功能恢复的关系 将会被调查。糖酵解能量生产在人体内的重要性 在缺血和再灌注期间维持阳离子梯度将是 调查过了。将采用两种不同的缺血模型，均为低血压。 血流和零血流全脑缺血。Na+/H+交换的作用将 通过使用特定的抑制剂直接进行调查 乙基异丙基阿米洛利。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- 以配对的Wistar-京都大鼠为对照，考察其敏感性。 从肥厚的心脏到缺血。钙离子作为血管紧张素转换酶调节因子的作用 可以阐明细胞损伤，从而更好地理解 关于心肌缺血的可能治疗方法。

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.