Taylor D E, Kantrow S P, Piantadosi C A
Department of Medicine, University of Texas-Houston Medical Center, Houston, Texas 77030, USA.
Am J Physiol. 1998 Jul;275(1):L139-44. doi: 10.1152/ajplung.1998.275.1.L139.
Recently, marked oxygen dependence of respiration by isolated mitochondria after exposure to prolonged hypoxia has been described. Because mitochondrial oxygen-dependent respiration could significantly influence oxygen consumption during critical illness, we sought to confirm the oxygen-dependent behavior of mitochondria. We hypothesized that mitochondria isolated during sepsis would exhibit increased oxygen dependence. We isolated rat liver mitochondria 16 h after cecal ligation and puncture and found a 30-40% greater oxygen uptake compared with control rats under state 3 conditions. Mitochondria incubated in deoxygenated buffer were studied for oxygen dependence at 10-min intervals for 90 min. Mitochondrial respiration after reoxygenation was stable over a 60-min period of hypoxia for control rats and decreased slightly for septic rats (10-15%). State 3 respiration was 10% lower when mitochondria were reoxygenated at low (15-25 Torr) versus high (90-100 Torr) and low (10-15 Torr) versus intermediate (40-45 Torr) oxygen tension. Oxygen consumption with ascorbate+N, N, N', N'-tetramethyl-p-phenylenediamine was 20% lower at low versus high oxygen tension. No increase in oxygen dependence was observed during 1 h of hypoxic incubation. Our data indicate only a modest oxygen dependence of respiration between 10 and 100 Torr, which is similar for septic and control mitochondria. Additionally, oxygen dependence did not increase significantly during a 1-h hypoxic exposure for well-coupled mitochondrial preparations.
最近，有研究描述了长时间缺氧后分离的线粒体对氧气的显著依赖性呼吸作用。由于线粒体的氧依赖性呼吸作用可能会对危重病期间的氧气消耗产生重大影响，我们试图证实线粒体的氧依赖性行为。我们假设脓毒症期间分离的线粒体将表现出更高的氧依赖性。我们在盲肠结扎和穿刺16小时后分离大鼠肝脏线粒体，发现在状态3条件下，与对照大鼠相比，其氧气摄取量增加了30%-40%。在脱氧缓冲液中孵育的线粒体每隔10分钟研究一次氧依赖性，共研究90分钟。复氧后，对照大鼠的线粒体呼吸在60分钟的缺氧期内保持稳定，而脓毒症大鼠的线粒体呼吸略有下降（10%-15%）。当线粒体在低氧（15-25托）与高氧（90-100托）以及低氧（10-15托）与中等氧（40-45托）张力下复氧时，状态3呼吸降低了10%。在低氧与高氧张力下，抗坏血酸+N，N，N'，N'-四甲基对苯二胺的耗氧量降低了20%。在缺氧孵育1小时期间未观察到氧依赖性增加。我们的数据表明，在10至100托之间，呼吸作用仅存在适度的氧依赖性，脓毒症线粒体和对照线粒体相似。此外，对于偶联良好的线粒体制剂，在1小时的缺氧暴露期间，氧依赖性没有显著增加。
