Honzik T, Wenchich L, Böhm M, Hansikova H, Pejznochova M, Zapadlo M, Plavka R, Zeman J
Department of Paediatrics and Neonatology, Faculty of Medicine, Charles University, Ke Karlovu 2, Prague, Czech Republic.
Early Hum Dev. 2008 Apr;84(4):269-76. doi: 10.1016/j.earlhumdev.2006.07.008. Epub 2007 Aug 14.
Most diseases in premature neonates are secondary to immaturity of various organ systems. Also the inadequate capacity of mitochondrial energy production may play an important role in the neonatal morbidity.
The activities and amount of respiratory chain (RC) complexes, pyruvate dehydrogenase (PDH) and citrate synthase (CS) were analysed in isolated muscle mitochondria obtained at autopsy in 19 premature neonates using spectrophotometric and radioenzymatic methods and blue-native electrophoresis and Western blotting. Two groups of children recommended for muscle biopsy at the age of 0.5-2 and 3-18 years served as controls.
In premature neonates, the activities of RC complexes III, IV, PDH and CS were markedly lower in comparison with older children. On the contrary, the activity of complex I was higher in premature neonates than in older children. The ratios between RC complexes I, II and III and CS were significantly higher in premature neonates in comparison with older children. In addition, the protein amount of RC complexes and PDH subunits were lower in premature neonates in comparison with older children.
The results of our study document the age-dependent differences in activities of PDH and respiratory chain complexes in early childhood. Lower functional capacity of mitochondrial energy-providing system in critically ill neonates may be explained by combination of various factors including the delay in maturation of PDH and respiratory chain complexes in very premature neonates and increased degradation of mitochondrial proteins in connection with sepsis, tissue hypoperfusion or hypoxemia.
大多数早产儿疾病继发于各器官系统发育不成熟。此外，线粒体能量产生能力不足可能在新生儿发病中起重要作用。
采用分光光度法、放射酶法、蓝色非变性电泳和蛋白质印迹法，对19例早产儿尸检时获取的分离肌肉线粒体中的呼吸链（RC）复合物、丙酮酸脱氢酶（PDH）和柠檬酸合酶的活性及含量进行分析。两组分别为0.5 - 2岁和3 - 18岁推荐进行肌肉活检的儿童作为对照。
与大龄儿童相比，早产儿的RC复合物III、IV、PDH和CS的活性明显较低。相反，早产儿中复合物I的活性高于大龄儿童。与大龄儿童相比，早产儿中RC复合物I、II和III与CS之间的比率显著更高。此外，与大龄儿童相比，早产儿中RC复合物和PDH亚基的蛋白含量较低。
我们的研究结果证明了儿童早期PDH和呼吸链复合物活性存在年龄依赖性差异。危重新生儿线粒体能量供应系统功能较低可能由多种因素共同作用导致，包括极早产儿中PDH和呼吸链复合物成熟延迟，以及与败血症、组织灌注不足或低氧血症相关的线粒体蛋白降解增加。
