Mitochondrial energy metabolism in very premature neonates.

The activity, amount and protein composition of pyruvate dehydrogenase (PDH) and respiratory chain complexes were studied in muscle mitochondria obtained postmortally from 6 neonates with a gestational age of 23-29 weeks. The activities of PDH and respiratory chain complex III and IV and citrate synthase were significantly lower in comparison with control children aged 0.5-2 and 2-20 years. Protein analyses revealed a parallel decrease in the content of PDH, respiratory chain complexes and their subunits in the cases analyzed. The observed immaturity of the mitochondrial energy-providing system suggests that significant development of mitochondrial energy metabolism occurs during the last 3 months of prenatal development. The metabolic disturbances of mitochondrial energy conversion associated with the low functional capacity and content of PDH and respiratory chain complexes may play an important role in the morbidity of very premature neonates.