Hardy L, Clark J B, Darley-Usmar V M, Smith D R, Stone D
Biochemistry Department, St. Bartholomew's Hospital Medical College, London, U.K.
Biochem J. 1991 Feb 15;274 ( Pt 1)(Pt 1):133-7. doi: 10.1042/bj2740133.
Reoxygenation of the hypoxic myocardium results in a number of processes, including an O2-dependent increase in total tissue Ca2+ and cell lysis in which mitochondrial electron transport plays a key role. In the present study we have isolated mitochondria from perfused rat hearts subjected to hypoxia and found no change in their respiratory function relative to controls. In contrast, mitochondria isolated immediately after reoxygenation of hypoxic-perfused hearts exhibited a specific and significant decrease in NADH:CoQ reductase (Complex I; EC 1.6.5.3) activity, as measured both polarographically and spectrophotometrically. Isolated cardiomyocytes subjected to a similar protocol of hypoxia/reoxygenation also exhibited a specific decrease in Complex I activity. Myocardial perfusion with media containing Ruthenium Red protected against the reoxygenation-dependent loss of Complex I activity. These observations taken together suggest that mitochondrial Ca2+ uptake on reoxygenation is implicated in the mechanism of the specific loss of Complex I activity.
缺氧心肌的再灌注会引发一系列过程，包括组织总钙含量的氧依赖性增加以及细胞裂解，其中线粒体电子传递起着关键作用。在本研究中，我们从经历过缺氧的灌注大鼠心脏中分离出线粒体，发现其呼吸功能与对照组相比没有变化。相反，在缺氧灌注心脏再灌注后立即分离的线粒体，通过极谱法和分光光度法测量，其NADH：辅酶Q还原酶（复合体I；EC 1.6.5.3）活性出现了特异性且显著的下降。经历类似缺氧/再灌注实验方案的分离心肌细胞也表现出复合体I活性的特异性下降。用含钌红的培养基进行心肌灌注可防止再灌注依赖性复合体I活性丧失。综合这些观察结果表明，再灌注时线粒体对钙的摄取与复合体I活性特异性丧失的机制有关。
