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A Study On The Mechanisms Of Oxidative Stress And Hypoxic Acclimatization In Rats During Intermittent Hypoxic Training

Posted on:2004-08-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:L Y HuangFull Text:PDF
GTID:1117360092997383Subject:Human Movement Science
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A Study on the Mechanisms of Oxidative Stress and Hypoxic Acclimatization in Rats during Intermittent Hypoxic TrainingSpecialty: Human Sports Science Postgraduate: Huang Liying Tutor: Prof. Xu HaowenThe mechanisms of oxidative stress and hypoxic acclimatization in rats during intermittent hypoxic training were studied at cellular, molecular and genetic levels.One hundred and twenty male Sprague-Dawley rats (8 weeks old) were randomly divided into three groups: normoxia group, acute hypoxia group and intermittent hypoxic group. Normoxia group included normoxia control and normoxia training sub-groups; acute hypoxia group included acute hypoxia control, acute hypoxia exercise and acute hypoxia training sub-groups; intermittent hypoxic group included intermittent hypoxic control and intermittent hypoxic training sub-groups. Therefore there are totally 12 sub-groups, each one with 10 rats. During the 4 weeks experimental period, we employed the 14.5% and 12.6% concentrations of oxygen (equal to altitude 3000m and 4000m respectively) in the hypoxic chamber. The rats of acute hypoxia training were introduced to treadmill running on an incline of 0 at 25m/min for Ih every day for 4 weeks. The rats of intermittent hypoxic were exposed to hypoxia for 12h every day for 4 weeks, In addition of that, intermittent hypoxic training rats were kept running out of chamber with Ih training bouts at the speed of 25m/min every day. Just before sacrificed, the rats of acute hypoxia and intermittent hypoxic were exposed to hypoxia for 12h(in which the acute hypoxia exercise rats were provided the training of running for Ih at the speed of 25m/min.).Myocardial ultrastructure of nucleus, mitochondria, myo fibrils, intercalated disc and capillary vessel were observed by transmission electron microscope during the hypoxic acclimatization experimental period. The results show that myocardial ultrastructures were damaged by acute hypoxic stress, and the damage in altitude 4000m sub-groups was severer than that in altitude 3000m sub-groups, in which theseverest was that in acute hypoxic exercise sub-group. The damages included decreases in electron density of ground substances, breakings of myofibril, eoaguation of mitochondria and disorder and blurring of mitochondria crista. Decrease of heterochromatin in nuclei was also observed. However, the damages of myocardial ultrastructure in rats of altitude 3000m were recoverable while those of altitude 4000m were not. These results suggest that: 1) acute hypoxic stress could induce myocardial ultrastructure damage. The severest damages in acute hypoxic exercise sub-groups may be caused by exercise together with hypoxia. The results indicate that there was close relationship between the damages of myocardial ultrastructure and hypoxia. The lower the content of oxygen is, the severer the damages are. 2) The damages to the rats exposed to hypoxia with 4-week training were alleviated, which suggests that training could protect myocardial cells from injury induced by hypoxia.3) Training and hypoxic acclimatization did not change myocardial ultrastructure. 4) The damages of myocardial ultrastructure were probably revivable in rats at altitude 3000m but were irrevivable in rats at altitude 4000m. The damages of myocardial ultrastructure in rats at altitude 3000m were reversible but those in rats at altitude 4000m were probably not. 5) Intermittent hypoxic training acclimatization could improve ultrastructure of nucleus, mitochondria, myofibrils, intercalated disc and capillary vessel. Therefore capacities of oxygen transport and energy utilization would be strengthened as a result.To investigate the changes of mitochondria metabolism induced by hypoxia, we used the techniques, such as spectrofluormeter and Chemiluminescencemeter, to assay the Ca2+concentration of mitochondria in the heart, liver and skeletal muscle tissue, ATP content and ATPase activity of mitochondria in the heart tissue were assessed by spectrofluormeter and Chemiluminescencemeter. Results show that free C...
Keywords/Search Tags:hypoxia, training, hypoxic acclimatization, myocardial ultrastructure, mitochondria, energy metabolism, oxygen transport, oxidative stress, gene regulation
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