低氧复合常氧训练增强大鼠腓肠肌琥珀酸脱氢酶的活性

背景低氧训练对骨骼肌能量代谢的影响是运动医学的研究热点.而目前有关低氧训练改善骨骼肌有氧氧化、无氧代谢能力的证据并不充分.目的探讨低氧复合常氧训练对骨骼肌有氧和糖酵解能力的影响.设计随机实验观察.单位北京体育大学运动人体科学学院.材料实验于2003-03/07在河北体育科学研究所完成.选择7周龄健康雄性SD大鼠96只,随机分为4大组对照组、低氧对照组、低氧复合常氧训练组和常氧训练组.根据实验组4,7,28 d取样时间的不同,将每大组随机分成3小组,每组8只.方法建立模拟海拔4 000米中等强度低氧复合常氧训练4周的动物模型(跑台坡度10%,跑速20m/min,1次/d,1h/次,5次/周,共4周),剪取腓肠肌肌腹红白混合处约0.5 g,经处理后待测.采用紫外分光光度法测定10%腓肠肌匀浆液中琥珀酸脱氢酶活力.腓肠肌乳酸脱氢酶活性采用半自动生化分析仪内设的"速率法",测定0.5%腓肠肌匀浆液中乳酸脱氢酶活力.总蛋白浓度采用半自动生化分析仪内设的"终点法"-双缩脲法.主要观察指标在不同观察时间腓肠肌琥珀酸脱氢酶和乳酸脱氢酶活性的变化.结果实验过程中无动物死亡,全部进入结果分析.①单纯低氧刺激可以引起琥珀酸脱氢酶活性升高,但随时间推移呈逐渐降低趋势;而低氧复合常氧训练使琥珀酸脱氢酶活性在4～28 d的各观察期都显著升高,且与单纯低氧间呈剪刀式变化.其中在第28天观察时比对照组高约2倍.②单纯低氧刺激、单纯常氧训练都使乳酸脱氢酶活性降低;而低氧复合常氧训练的乳酸脱氢酶活性基本稳定在对照水平.结论模拟海拔4 000m,中等强度的低氧复合常氧训练,4周时间内即可提高腓肠肌琥珀酸脱氢酶活性.预示低氧复合常氧训练能提高骨骼肌有氧代谢潜能.同样训练环境和运动负荷,未能提高腓肠肌乳酸脱氢酶活性,即4周的低氧复合常氧训练未必能改善骨骼肌糖酵解供能能力.

Enhanced activity of succinate dehydrogenase in rat's gastrocnemius under hypoxic living with normoxic training

BACKGROUND: The effect of hypoxic training on energy metabolism of skeletal muscles is receiving much interest from researchers of sports medicine. But at present, sufficient evidence supporting hypoxic training for its improvement on skeletal muscle aerobic oxidation and anaerobic capacity has not been obtained.OBJECTIVE: To investigate the effect of hypoxic living with normoxic training on aerobic oxidation and glycolytic capacity of rat skeletal muscles.DESIGN: Randomized controlled experiment.SETTING: College of Human Sport Science of Beijing Sport University.MATERIALS: This experiment was carried out in the Hebei Institute of Sport Science between March and July, 2003. Totally 96 normal male SD rats of 7 weeks were randomized into control group (C), hypoxic control group (HC), hypoxic living with normoxic training group (HNT) and normoxic training group (NT). The latter 3 groups were further divided into 3 subgroups (n=8) according to the sampling time points of 4, 7, and 28 days.METHODS: Hypoxic living with normoxic training protocol was designed to simulate the moderate-intensity normoxic training with hypoxic living for 1 hour in the condition of 4000 m altitude (with the slope of the treadmill of 10%, speed of 20 m/minutes performed once daily, 5 times a week for 4 consecutive weeks). Gastrocnemius muscle samples (0.5 g) were collected at the conjunction of the red and white tissues from the rats at the specified time points. Ultraviolet spectrophotometry was used to determine the activity of succinate dehydrogenase (SDH) in 10% gastrocnemius muscular homogenate. Gastrocnemius lactate dehydrogenase (LDH) activity was assayed by the "rate method" in the mode setting of the semi-automatic biochemical analyzer. The total protein density was determined with "endpoint method" with the analyzer, namely biuret method.MAIN OUTCOME MEASURES: Changes of the activity of SDH and LDH in rat gastrocnemius muscles at different time points.RESULTS: None of the animals died during the experiment and all entered the result analysis. Hypoxia .alone could increase SDH activity,which, however, tended to decrease with time. In contrast, hypoxic with normoxic training obviously increased SDH activity during the entire period of 4-28 days, and the changes in SDH, along with those in hypoxia group, depicted two curves crossing each other in the fashion of a scissor.At day 28, SDH activity was approximately twice as high as that of the control group. Both hypoxic alone and normoxic training alone could reduce LDH activity, with remained stable at around the normal level in rats with hypoxic living with normoxic training normoxic training.CONCLUSION: Hypoxic living with normoxic training can promote the aerobic metabolic potential but has no significant effect on LDH activity in rats under the same training condition and exercise load, in other words, the glycolytic capacity of the skeletal muscle can not be necessarily improved after 4-week hypoxic living with normoxic training normoxic training.