A Study On The Gene Expression Of ND1 And ND2 Subunit Of Mitochondrial Respiratory Chain On Heart And Intestine Cells Of Rat Under Hemorrhagic Shock

Mitochondrion is not only the center providing energy that necessitates cell life activities, but also a sensitive and mutable cell organ. It differs in number, structure and function under different physiological and patho-physiological circumstances. The OXPHOS (oxidative phosphorylation) in mitochondria generates most of energy used by cells under physiological conditions, while trauma as well as hemorrhagic shock causes hypoxia and ischemia, which finally falls into irreversible disturbance of energy metabolism. During the pathological process, the permeability of cell membrane changed, the edema of mitochondria appeared and the activity of respiratory complex enzymes decreased. Mitochondrial DNA (mtDNA) is the semi-autonomous genome independent of the nuclear genome, and due to its special features (located in the mitochondrial matrix where is the powerful source of ROS(reactive oxygen species), lack of protection by the histone and effective repair mechanism when damaged), it has made the mtDNA-encoded genes an important target for the pathologic factors such as hypoxia and ischemia.The relationship between the mitochondrial DNA deletions or mutations and human diseases has appealed a lot of interest since the complete mtDNA was sequenced in 1981. Up to now there are nearly 100 kinds of mtDNA mutations or deletions have been confirmed relative with mitochondrial myopathy, mitochondrial cerebral myopathy, Alzheimer's disease, LHON (Leber's hereditary neuropathy), diabetes mellitus and cerebral ischemic disease, etc. And finding effective cures to these diseases caused by dysfunction of mitochondria has become a hot spot and still remains a great obstacle to conquer.The changes on ultrastructure in mitochondria and the respiratory chain enzyme activities were usually taken on as significant indices to evaluate the energy level in the cell. However, would the level of gene expression and gene sequences alter when injury, burn, or hemorrhagic shock occurred? And are these changes directly related with the function and structure of mitochondria? All mentioned above has not been reported systematicallyyet. Mitochondrial respiratory chain complex Ⅰ(NADH dehydrogenase ) is the largest enzyme complex with the most complicated structure among the five complexes ,which contains over 40 subunit polypeptide encoded by both nuclear and mitochondrial genomes . There are 7 subunits of respiratory complex I encoded by mitochondrial gene: ND1～ ND6, ND 4L .Of the 13 polypeptides in the respiratory chain encoded by mtDNA, complex I hold the largest proportion (7/13), and so far sufficient proof has been presented to demonstrate close relationships between the changes of the 7 subunits of complex and ischemia, stress and degenerative nerve disease. And mitochondrial complex I also has been found to be one of the main sources of the superoxide radicals, which makes itself more vulnerable to the impairment of ROS.Mitochondrial transcription factor A(mtTFA) is one of the key regulators involved in mitochondrial DNA transcription and replication. MtTFA plays an important role in maintaining mtDNA content and the intactness of the respiratory function of mitochondria through binding to unique sequences of mtDNA and initiating its replication and transcription.Heart and intestine tissues are two important target organs in the process of hypoxia and ischemic damages. And lots of studies had been done well on research of their roles played in ARDS,MODS,endotoxemia,burn,etc, but the research on the differences of the two tissues under pathological circumstances is relatively rare.In this study ,we took on the hemorrhagic shock rat as our animal model ,and utilized RT-PCR,PCR and DNA sequencing as well as light microscopy, electronic microscopy　and Clark oxygen electrode to explore the patterns on the changes of expression and base pairs of the ND1 and ND2 genes in heart and intestine cells.The main results and conclusions are as follows: 1. 1h~2h after hemorrhagic shock, the transcription...