NMR STUDIES OF THE MECHANISMS OF CELL INJURY

在体内和原位核磁共振研究进行了系统， 从细胞悬液到灌注器官，再到完整的、麻醉的 实验动物，以确定机制， 环境化学品和其他类型的压力不可逆转 损伤细胞。 生理生化和磁共振 测量在可能的情况下并行进行， 验证所使用的技术，更重要的是， 各种代谢变化，以确定哪些因素可能 起一个因果作用。 最近有人提出， 细胞溶质钙离子水平的扰动可能是 在产生不可逆细胞损伤中的核心重要性 由多种因素引起，作为激活的结果， 各种分解代谢，钙依赖酶，如钙蛋白酶和 磷脂酶 细胞内钙离子水平的变化 制备，特别是灌流的大鼠心脏，已经确定 基于使用氟-19 NMR测量心脏负荷 氟化钙螯合剂。 使用这种方法， 测定舒张期钙水平为150 mM。 钙在缺血15分钟后上升至约2.5 μ M， 时间短于不可逆地损害所需的时间， 心脏，由细胞酶的泄漏决定。 操作，如引入钙通道阻滞剂， 心脏停搏和低温，这会延迟 不可逆转的伤害，都相应地推迟了 胞浆钙

In vivo and in situ NMR studies are carried out on systems ranging from cell suspensions to perfused organs, to intact, anesthetized experimental animals in order to determine the mechanisms by which environmental chemicals and other types of stress irreversibly injure cells. Physiological, biochemical, and magnetic resonance measurements are carried out in parallel when possible, both to validate the techniques used, and more importantly, to correlate various metabolic changes in order to determine which factors may play a causative role. It has recently been suggested that perturbations in the level of cytosolic calcium ions may be of central importance in the production of irreversible cell injury arising from a variety of agents as a consequence of the activation of various catabolic, calcium dependent enzymes such as calpain and phospholipases. The level of cytosolic calcium ions in various preparations, particularly perfused rat hearts, has been determined based on the use of fluorine-19 NMR measurements of hearts loaded with fluorinated calcium chelator. Using this approach, the diastolic calcium level was determined to be 150 mM. Cytosolic calcium rose to approximately 2.5 uM after 15 minutes of ischemia, a time period shorter than required to irreversibly injure the heart, as determined by the leakage of cellular enzymes. Manipulations such as the introduction of calcium channel blockers, cardioplegic arrest, and low temperature, which delay the onset of irreversible injury, all correspondingly delay the rise of cytosolic calcium.