Sims N R, Finegan J M, Blass J P
J Neurochem. 1986 Aug;47(2):506-11. doi: 10.1111/j.1471-4159.1986.tb04530.x.
Mitochondria isolated from ischemic brain characteristically show changes in respiratory function. As conventional procedures for mitochondrial isolation yield a subpopulation of the total population and require extensive manipulation, it is unclear to what extent these changes are representative of mitochondria in the unfractionated tissue. We previously showed that the oxygen uptake by unfractionated forebrain homogenates, measured under two different sets of incubation conditions, provided information on some aspects of the respiratory activity of both the free and synaptosomal pools of mitochondria. Forebrain homogenates from animals subjected to 30 min of postdecapitative ischemia exhibited large reductions in oxygen uptake rates measured in a high K+ (mitochondrial) buffer in the presence of either ADP (44% of control values) or an uncoupling agent (45% of control values). These reductions in respiratory activity were comparable to alterations observed under the same conditions for mitochondria isolated from the ischemic brains. Similar alterations were seen in homogenates from three subregions: neocortex, hippocampus, and striatum. In a physiological buffer, in which oxygen uptake by homogenates largely resulted from activity of mitochondria within synaptosomes, there was little or no change in basal glucose-supported rates (79-96% of control values) and small reductions in maximal rates (63-81% of control values) measured in the presence of an uncoupling agent. These results suggest that alterations of respiratory function seen in isolated free mitochondria provide appropriate estimates of the dysfunction in the total free mitochondrial pool but that synaptosomal mitochondria may be less affected. Measurements of respiratory function of isolated synaptosomes from ischemic tissue provided further support for the relative preservation of synaptosomal mitochondria during ischemic insult.
从缺血性脑分离出的线粒体表现出呼吸功能的特征性变化。由于传统的线粒体分离程序只能得到总群体中的一个亚群，且需要大量操作，因此尚不清楚这些变化在多大程度上代表了未分级组织中线粒体的情况。我们之前表明，在两种不同的孵育条件下测量的未分级前脑匀浆的氧摄取，提供了关于线粒体游离池和突触体池呼吸活动某些方面的信息。在断头后缺血30分钟的动物的前脑匀浆中，在高钾（线粒体）缓冲液中，无论存在ADP（对照组值的44%）还是解偶联剂（对照组值的45%），测得的氧摄取率都大幅降低。这些呼吸活动的降低与从缺血性脑分离出的线粒体在相同条件下观察到的变化相当。在三个亚区域（新皮层、海马体和纹状体）的匀浆中也观察到了类似的变化。在生理缓冲液中，匀浆的氧摄取主要来自突触体内线粒体的活动，基础葡萄糖支持率几乎没有变化（对照组值的79 - 96%），在存在解偶联剂时测得的最大速率略有降低（对照组值的63 - 81%）。这些结果表明，在分离的游离线粒体中看到的呼吸功能改变能适当估计总游离线粒体池中的功能障碍，但突触体线粒体可能受影响较小。对缺血组织中分离出的突触体呼吸功能的测量进一步支持了突触体线粒体在缺血损伤期间相对保持完好的观点。
