NMR STUDIES OF THE MECHANISMS OF CELL INJURY

这项研究的重点是离子改变的作用， 不可逆细胞损伤的发展。我们利用活体和原位 细胞悬浮液和灌注器官的NMR方法，以确定 这些离子的胞质浓度，并监测相关的 NMR技术对其敏感的代谢变化。我们有 先前证明，细胞溶质钙（Ca-1，钠）的增加， （Na-1）、镁（Mg-1）和氢，并且在ATP减少期间发生。 细胞损伤尽管人们似乎正在形成一种共识， 在Ca-i之前发生不可逆损伤，这并不能证明， Ca-i的增加是必要的或负责的发病， 不可逆的细胞损伤因此，我们进行了研究， 是否有可能操纵实验条件来防止或 延缓钙离子的增加。本实验采用离体大鼠心脏， 条件：完全缺血，钾停搏，镁停搏，和 用0.9 μ M地尔硫卓预处理以降低但不消除收缩性。 在所有测试条件下，Ca-1的增加先于致死性损伤， 由酶释放决定。因此，我们无法将 不可逆细胞损伤导致钙增加。 用核磁共振灵敏指示剂5 FBAPTA测定Ca ~（-1）， 表明阿米洛利显著减弱Ca-1的增加， 在缺血期间观察到。此外，由于ATP，通过31 p NMR测量， 在存在和不存在阿米洛利的情况下，福尔斯以相似的时间过程下降， 因此，我们可以将Ca-1的增加与ATP的减少分开。 我们观察到在缺血期间阿米洛利的存在可以更好地 20分钟后再流期间收缩功能的恢复 缺血这些数据有力地表明，钙离子浓度的上升对 在缺血后发生的收缩功能障碍中起重要作用。

This research is focused on the role of ionic alterations in the development of irreversible cell injury. We make use of vivo and in situ NMR methods on cell suspensions and perfused organs in order to determine the cytosolic concentrations of these ions and to monitor associated metabolic changes to which the NMR technique is sensitive. We have previously demonstrated that increases in cytosolic calcium (Ca-i, sodium (Na-i), magnesium (Mg-i), and hydrogen and a decrease in ATP occur during cell injury. Although a consensus appears to be developing that an increase in Ca-i precedes the onset of irreversible injury, this does not prove that an increase in Ca-i is necessary or responsible for the onset of irreversible cell injury. We therefore undertook studies to determine whether it was possible to manipulate experimental conditions to prevent or delay an increase in Ca-i. The perfused rat heart was studied under conditions of: total ischemia, potassium arrest, magnesium arrest, and pretreatment with 0.9 uM diltiazem to reduce but not abolish contractility. In all conditions tested, the increase in Ca-1 preceded lethal injury, as determined by enzyme release. Thus, we have not been able to dissociate the increase in calcium from irreversible cell injury. Using the NMR sensitive indicator 5FBAPTA to measure Ca-i, we have also demonstrated that amiloride significantly attenuates the increase in Ca-1 observed during ischemia. In addition, since ATP, measured by 31 p NMR, falls with a similar time course in the presence and absence of amiloride, we can therefore dissociate the increase in Ca-i from the decrease in ATP. We observed that the presence of amiloride during ischemia allows better recovery of contractile function during reflow after 20 minutes of ischemia. These data strongly suggest that the rise in Ca-i plays an important role in the contractile dysfunction which occurs after ischemia.