NMR STUDIES OF THE MECHANISMS OF CELL INJURY

这项研究的目的是阐明关键的细胞变化， 导致不可逆的细胞损伤 必须了解这些机制 才能提出合理的干预措施。 此前，我们已经展示了 胞浆游离钙的增加与细胞损伤有关。 在许多系统中，已经观察到细胞或动物暴露于 一个短暂的压力提供了相当大的保护，防止随后的更多的压力。 严重的压力 这种短暂的压力会导致 应激蛋白的合成;然而，尽管鉴定出 这些蛋白质，很少有人了解的机制， 保护 将灌注的大鼠心脏暴露于几个短暂的（5分钟） 缺氧应激（称为预处理）的时间提供了 当这些预处理的心脏受到更长的30-60 一分钟的缺氧压力，使预处理的心脏 与未治疗相比，坏死更少，功能恢复更好 对照 使用31 P核磁共振（NMR），我们已经确定 预处理降低ATP利用率;预处理 心脏的ATP下降速度较慢， 糖酵解 此外，使用31 P NMR和19 F NMR的组合（以 测量细胞内钙），我们已经确定， 代谢导致H+产生减少，因此Na/H和Na/Ca减少 交换和最终细胞溶质游离钙的增加较少。 我们 结论是，至少部分预处理的保护作用是 因为钙超载减少了 我们有兴趣解决 导致ATP利用率降低的机制。 我们有 研究假设腺苷是介导 预处理;然而，在灌注的大鼠心脏腺苷不出现 因为我们无法用一种 腺苷拮抗剂 此外，我们无法阻止 通过添加格列本脲进行预处理，从而排除了 ATP敏感性钾通道是这一过程的一部分。

The goal of this research is to elucidate the critical cellular changes that lead to irreversible cell injury. These mechanisms must be understood before rational interventions can be proposed. Previously, we have shown that an increase in cytosolic free calcium is associated with cell injury. In many systems, it has been observed that exposure of cells or animals to a brief stress provides considerable protection against a subsequent more severe stress. This brief period of stress is known to result in the synthesis of stress proteins; however, in spite of the identification of these proteins, there is little understanding of the mechanisms of protection. Exposing perfused rat heart to several brief (5 minute) periods of anoxic stress (referred to as preconditioning) affords protection when these preconditioned hearts are subjected to a longer 30-60 minute period of anoxic stress such that the preconditioned hearts have less necrosis and better recovery of function compared to untreated controls. Using 31P nuclear magnetic resonance(NMR) we have determined that preconditioning decreased the rate of ATP utilization; preconditioned hearts have a slower rate of decline in ATP and a reduced rate of anaerobic glycolysis. In addition, using a combination of 31P NMR and 19F NMR (to measure intracellular calcium) we have determined that the reduced metabolism results in less H+ production, and therefore less Na/H and Na/Ca exchange and ultimately less of an increase in cytosolic free calcium. We conclude that at least part of the protective effect of preconditioning is due to reduced calcium overload. We were interested in addressing the mechanism(s) responsible for the reduced rate of ATP utilization. We have investigated the hypothesis that adenosine is the mediator of preconditioning; however, in perfused rat heart adenosine does not appear to play such a role since we were unable to block the effect with an adenosine antagonist. In addition, we were not able to block preconditioning by the addition of glibenclamide, thus ruling out a role for the ATP sensitive K channels as part of this process.