文本框: CYTOCHROME C OXIDASE ACTIVITY IN NEONATAL PIG HIPPOCAMPAL CORTEX AFTER HYPOXIC-ISCHEMIA Fu X*,Li W# Second University Hospital, West China University of Medical Sciences, Chengdu, China *postgraduate, # turor Objective: To study the cytochrome c oxidase (COX) activity in neonatal pigs’hippocampal cortex after 2h hypoxic-ischemia. Methods: Fifty three-day pigs were randomly assigned to 5 groups. Group I was control group which was exposed to normoxic atmosphere, the others were treatment groups which were performed brain hypoxia-ischemia by ligated left common carotid artery and then exposed to O2 8%, N2 92% for two hours, then put into normoxic atmosphere.According to the different time of normoxic atmosph-ere, they were divided into four groups (0h group II, 24h groupIII, 48h group IV and 72h group V). Every pig was examed the COX activity in hippocampal cortex of ligated side by near-infrared spectroscopy. Results: the COX activity didn't change in the group II when compared to group I. With reoxgenation it began to decline, the lowest point of it was in group III, and then it began to restore, but it did not reture to normal values in group V. Conclusion: These date show that the COX activity of neonate animals remains unchanged after 2 hrs brain hypoxia-ischemia, but not in reoxygenation. This adds to the growing body of evidence that mitochondrial play a key role in neuronal apoptosis/necrosis following cerebral hypoxia-ischemia/reoxygenation. It is the theoretical basis for searching of the “therapeutic time window” following hypoxic-ischemia in which it is possible to intervene in order to limit mitochondria and hence cellular damage. 0773