缺氧及缺氧复合运动大鼠骨骼肌组织化学观察

用酶组织化学方法观察了缺氧及在缺氧条件下运动对大鼠腓肠肌肌纤维形态和毛细血管的影响。结果表明 ,单纯慢性缺氧动物骨骼肌纤维萎缩 ,毛细血管密度显著增加 ,毛细血管 /肌纤维 (C/F)的比值无明显变化 ;动物在缺氧条件下运动 5周 (1小时 /天 ,6天 /周 )后 ,骨骼肌纤维不发生萎缩 ,毛细血管密度增加 ,C/F明显升高。说明单纯缺氧时 ,骨骼肌毛细血管并未发生增生 ,而在缺氧条件下运动才会伴有毛细血管的新生。     

支链氨基酸对运动大鼠骨骼肌线粒体功能的影响

为探讨支链氨基酸(BCAA)对提高大鼠运动能力的作用,本实验取雄性wistar大鼠21只,随机分为正常组、游泳对照组和游泳补充5%支链氨基酸饲料组.两个游泳组每天游泳训练l小时.10天后,游泳6小时,测定血和骨骼肌乳酸水平,测定骨骼肌糖原含量、骨骼肌线粒体脂质过氧化物(LP0)水平和线粒体膜的流动性以及线粒体矿物元素钙(Ca)、镁(Mg)、钾(K)含量.结果显示BCAA可抑制游泳运动后大鼠的血和骨骼肌乳酸的升高幅度,减少骨骼肌糖原的降低幅度与骨骼肌线粒体LP0的升高幅度,抑制骨骼肌线粒体膜流动性和矿物质元素Ca、Mg、K含量的下降.以上结果表明,BCAA可改善运动后骨骼肌线粒体功能,对抗运动性疲劳.可能有利于提高大鼠的运动能力.     

骨骼肌线粒体运动适应的分子机制

运动训练可对骨骼肌产生深刻影响,长期反复刺激可使骨骼肌发生适应性改变。而骨骼肌线粒体作为骨骼肌的动力来源,为骨骼肌行使正常功能提供保障,其对运动产生的适应性变化表现为:适宜的运动可促进骨骼肌线粒体生物合成,加速受损或老化线粒体的降解,改变线粒体动力学,重构线粒体网络。对骨骼肌线粒体运动适应机制的研究表明,运动可通过调控过氧化物酶体增殖因子激活受体共激活因子-1α(PGC-1α)、有丝分裂原活化蛋白激酶(P38MAPK)、腺苷单磷酸活化蛋白激酶(AMPK)等因子及其相关信号通路促进线粒体生物合成;运动还可通过影响线粒体融合蛋白、分裂蛋白及AMPK的表达,促进线粒体自噬,以清除损伤或老化的线粒体。通过线粒体新生与损伤线粒体降解,可使线粒体功能增强,线粒体网络结构重构,从而满足运动需求。     

运动、Nrf2与骨骼肌线粒体

骨骼肌线粒体供能能力和运动密切相关。核因子E2相关因子2(nuclear factor erythroid 2-related factor 2,Nrf2)作为一种广泛存在于哺乳动物细胞内的转录因子,它不仅可以调节骨骼肌的氧化应激状态,而且还影响到线粒体的生物合成、呼吸作用及其自噬等多个方面。本文就近年来运动对Nrf2的激活作用及Nrf2对线粒体影响的最新研究进展进行综述,为运动促进健康的效应机制研究提供理论依据。     

运动诱导骨骼肌线粒体生物合成调控机制研究进展

骨骼肌线粒体对外界应激存在重塑适应,应对能量代谢需求,维持细胞稳态.运动促进骨骼肌线粒体生物合成,有利于维持运动中的能量代谢.以过氧化物酶体增殖物激活受体γ辅激活因子α(PGC-1α)为代表的促进线粒体生物合成的众多因子对运动比较敏感,运动后PGC-1α表达增加,被认为是运动促进线粒体生物合成的分子机制.近些年研究提示...     

运动与骨骼肌线粒体生物合成

骨骼肌收缩诱导线粒体生物合成,不仅可以有效地延缓运动性疲劳的发生,还可积极预防与年龄相关的退行性改变导致的肌肉功能下降。这一线粒体对运动的适应过程是核基因与线粒体基因共同参与调节的结果。本文综述了当前有关运动与线粒体生物合成分子机理,着重讨论了肌肉收缩引起的细胞启动信号及转录、转录因子的激活及线粒体生物合成的转录后机制等分子生物学过程。     

骨骼肌线粒体蛋白输入机制的运动适应性研究进展

线粒体具有基因半自主性,99%的线粒体蛋白均由n DNA编码,需要经过转录、翻译,通过存在于线粒体膜上的蛋白输入机制(PIM:protein import machinery)输入至线粒体的不同区域,发挥功能。线粒体蛋白输入路径主要包括:1)线粒体基质蛋白输入;2)线粒体外膜蛋白输入;3)线粒体内膜蛋白输入;4)线粒体膜间隙蛋白输入等4个通路。PIM是线粒体生物发生的物质保障,是维持骨骼肌线粒体发挥正常功能的重要环节。骨骼肌线粒体PIM的运动适应性研究将进一步揭示运动性线粒体生物发生的分子机制及运动诱发线粒体与其它细胞器之间的相互作用。     

缺氧及缺氧复合运动大鼠心肌酶适应性变化

目的:探讨缺氧及在缺氧条件下运动对大鼠心肌代谢酶活性的影响。方法:24只Wistar大鼠随机分为4组:平原对照组、单纯缺氧组、平原运动组和缺氧复合运动组。缺氧复合运动组大鼠持续暴露于模拟海拔5000m低压舱内5周,每天将低压舱模拟海拔高度调至4000m进行游泳运动1小时(6天/周),运动结束后调至模拟海拔5000m;单纯缺氧组大鼠在低压舱内相同模拟海拔高度饲养,但不进行游泳运动;平原运动组和平原对照组在平原环境下饲养,其中平原运动组每天游泳运动1小时(6天/周)。实验5周后末次运动结束后24小时处死大鼠,分离左、右心室,称重并计算左、右心室重量指数。组织匀浆测定左、右心室己糖激酶(HK)、琥珀酸脱氢酶(SDH)、柠檬酸合成酶(CS)和乳酸脱氢酶(LDH)活性。结果:与平原对照组比较,单纯缺氧组和缺氧复合运动组大鼠右心室重量指数、Hermann-Willson指数显著增加,缺氧复合运动组大鼠左心室指数显著增高。单纯缺氧组大鼠左心室肌组织氧化酶SDH、CS活性降低,而缺氧复合运动组与对照组比无显著差异,缺氧复合运动组CS活性与缺氧组比较显著增加。与平原对照组比较,单纯缺氧组大鼠右心室HK、CS、LDH活性显著降低,缺氧复合运动组LDH活性较单纯缺氧组无显著差异,CS、SDH活性则显著增加。结论:长期缺氧使心肌组织氧化酶和糖酵解酶活性不同程度降低,缺氧复合运动后酶活性恢复或增加,表明在缺氧条件下适度运动,可调节有氧氧化和无氧酵解酶活性,增强机体对缺氧环境的代谢适应性。     

大鼠低压缺氧心肌及线粒体腺苷酸含量及分布的变化

目的:探讨模拟高原低压缺氧暴露过程中大鼠心肌腺苷酸含量及分布变化特点.方法:雄性Wistar大鼠随机分为正常对照组、缺氧1、5、15和30d组.缺氧组于模拟海拔5000m高原低压舱内连续缺氧23h/d.提取心室肌线粒体,HPLC法测量腺苷酸含量.结果:缺氧5、15、30d组,心室肌组织及线粒体外ATP含量明显下降,缺氧1d和5d,心肌线粒体ATP含量降低,缺氧15d时恢复,缺氧30d时则再次降低.结论:高原低压缺氧可影响心肌腺苷酸含量和分布,可能是高原心功能异常的主要原因.     

不同运动方式对大鼠骨骼肌线粒体融合分裂基因及Mfn2、Drp1蛋白表达的影响

目的:比较长时间低强度耐力运动和大强度间歇性运动对骨骼肌线粒体融合分裂基因与蛋白表达的影响,探讨不同运动方式下线粒体管网发生运动适应的动力学差异。方法:30只大鼠随机分为安静组(Con,n=10)、耐力运动组(ET,n=10)、间歇性运动组(SIT,n=10)。间歇性运动组每天进行9～10次10s极量强度(≥42 m/min)间歇跑台运动,间歇时间30～60 s;耐力运动组每天进行30～60 min低强度(≤16.7 m/min)持续跑台运动;每周训练6天,训练8周。最后一次训练结束后休息24 h,安静状态下取腓肠肌,Real-time PCR检测线粒体融合基因Mfn1、Mfn2、OPA1与分裂基因Drp1、hFis1的mRNA表达;Western blot检测线粒体Mfn2、Drp1蛋白水平。结果:(1)ET组Mfn1 mRNA表达显著高于Con组(P<0.05),SIT组Mfn2 mRNA表达显著低于Con组(P<0.05),SIT组OPA1 mRNA表达显著高于ET组(P<0.05)。SIT组Drp1 mRNA表达显著高于Con组(P<0.05)和ET组(P<0.01),ET组和SIT组hFis1 mRNA表达均无显著变化。(2)SIT组线粒体Mfn2蛋白表达显著高于Con组(P<0.05),Drp1蛋白表达显著低于Con组(P<0.05)。结论:线粒体融合分裂基因以及线粒体Mfn2、Drp1蛋白对长时间低强度耐力运动和大强度间歇性运动有不同的适应机制,这来源于运动方案的差异。大强度间歇性运动可能通过Mfn2、Drp1基因转录与蛋白表达水平影响骨骼肌线粒体的融合与分裂;长时间低强度耐力运动可能通过Mfn1基因转录发挥类似作用。     

Voluntary muscle function after creatine supplementation in acute hypobaric hypoxia

PURPOSE: To determine whether creatine (Cr) supplementation improves muscle performance during exposure to acute hypobaric hypoxia. METHODS: Seven healthy men (28 +/- 6 yr, mean +/- SD) performed submaximal intermittent static knee contractions interspersed with maximal voluntary contractions (MVCs) every minute to exhaustion (approximately 50% of rested MVC force) in normoxia and hypobaric hypoxia (separated by 3 d) after supplementation with Cr (20 g.d(-1) for 7 d then 5 g.d(-1) for 4-7 d) or placebo (Pla) in a double-blind, randomized crossover study. A 5-wk period without supplementation separated treatments. Each test day, subjects performed two bouts (separated by 2 min) at their preset submaximal force, 32 +/- 4% rested MVC). RESULTS: Rested MVC force (860 +/- 66 N) and MVC force at exhaustion (396 +/- 27 N; 47 +/- 3% rested MVC) did not differ among treatments or environments (P > 0.05). For bout 1, endurance time was shorter in hypobaria (26 +/- 3 min) than normoxia (34 +/- 2 min) (P < 0.01), but did not differ between Cr (27 +/- 3 min) and Pla (33 +/- 3 min) (P > 0.05). MVC force returned to similar levels (P >0.05) in bout 2 after recovery in all four sessions (to approximately 615 N). For bout 2, endurance time also was shorter in hypobaria (7 +/- 1 min) than normoxia (9 +/- 1 min) (P < 0.03) but did not differ between Cr and Pla (P > 0.05). CONCLUSION: This study, which used an exercise model designed to impose the same target contraction force under all experimental conditions, found no effect of Cr on maximal force, muscle endurance, or recovery in normoxia or hypobaric hypoxia.     

运动预适应对急性低压低氧大鼠脑海马线粒体生物合成的影响

 目的 探讨运动预适应对急性低压低氧大鼠脑海马线粒体生物合成影响。方法 大鼠分为对照组(normal control group, NC)、急性低氧组(acute hypoxia group, AH)和运动预适应(exercise preconditioning,EP)联合急性低氧组(acute hypoxia group,AH),每组8只。EP联合AH组大鼠在常氧环境进行6周跑台训练,坡度5°, 速度17 m/min,60 min/d,5次/周。AH组和EP+AH大鼠置于低压低氧舱8 h,压力0.06 MPa,氧含量10%±2%。荧光定量PCR法检测mtDNA拷贝数,荧光探针法检测线粒体膜电位,ROS生成速率和ATP合成活力,Western blotting 检测PGC-1α、NRF-1和Tfam蛋白表达。结果 AH组大鼠脑海马mtDNA拷贝数为1.69±0.20,较NC组(1.00±0.13)明显增高;线粒体ROS产生速率为(9.49±1.25) pmol/(min·mg protein),较NC组值(4.83±0.66) pmol/(min·mg protein)明显增高;PGC-1α蛋白表达量为(189.24±21.77),较NC组(100.00±12.90)明显增高;线粒体膜电位为(4.51±0.65),较NC组(8.27±1.02)明显降低;差异均具有统计学意义(P＜0.05)。EP+AH组大鼠脑海马mtDNA拷贝数为(1.19±0.15),较AH组(1.69±0.20)明显降低;线粒体ROS产生速率为(6.01±0.93) pmol/(min·mg protein),较AH组值(9.49±1.25) pmol/(min·mg protein)明显降低;PGC-1α蛋白表达量为141.95±18.12,较AH组(189.24±21.77)明显降低;线粒体膜电位为(7.02±1.10),较AH组(4.51±0.65)明显升高;上述差异均具有统计学意义(P＜0.05)。结论 运动预适应可抑制急性低压低氧对线粒体生物合成的上调效应,同时改善线粒体能量代谢能力,抑制氧化应激。     

Effect of hypobaric hypoxia on fiber type composition of the soleus muscle in the developing rat.

The fiber type composition of the soleus muscle was investigated in male Sprague-Dawley rats exposed to hypobaric hypoxia of 460 mm Hg from 5 to 12 weeks of age. The muscle fibers were classified as fast-twitch oxidative (FO) and slow-twitch (S) on the basis of adenosine triphosphatase (ATPase) and succinate dehydrogenase (SDH) reactions. Intermediate fibers (INT) with intermediate ATPase and high SDH reaction intensities were also examined. A type shift of muscle fibers from FO to INT and S was found in the control group during development. After exposure to hypoxia, the hypoxia group had a significantly greater percentage of FO fibers than the age-matched control group. There was no significant change in the total number of fibers in the muscle during development and after exposure to hypoxia. These results indicate that the increased percentage of FO fibers found in the developing rat under hypoxic conditions is due to a hypoxia-induced inhibition of the type shift of muscle fibers from FO to S during development.     

Effects of low-load resistance training combined with blood flow restriction or hypoxia on muscle function and performance in netball athletes

ObjectivesTo investigate the effect of blood flow restriction or normobaric hypoxic exposure combined with low-load resistant exercise (LRE), on muscular strength and endurance.DesignA randomised controlled trial.MethodsWell-trained netball players (n = 30) took part in a 5 weeks training of knee flexor and extensor muscles in which LRE (20% of one repetition maximum) was combined with (1) an occlusion pressure of approximately 230 mmHg around the upper thigh (KT, n = 10), (2) hypoxic air to generate blood oxyhaemoglobin levels of approximately 80% (HT, n = 10) or (3) with no additional stimulus (CT, n = 10). The training was of the same intensity and amount in all groups. One to five days before and after training, participants performed a series of strength and endurance tests of the lower limbs (3-s maximal voluntary contraction [MVC₃], area under 30-s force curve [MVC₃₀], number of repetitions at 20% 1RM [Reps201RM]). In addition, the cross-sectional area (CSA) of the quadriceps and hamstrings were measured.ResultsRelative to CT, KT and HT increased MVC₃ (11.0 ± 11.9% and 15.0 ± 13.1%), MVC₃₀ (10.2 ± 9.0% and 18.3 ± 17.4%) and Reps201RM (28.9 ± 23.7% and 23.3 ± 24.0%, mean ± 90% confidence interval) after training. CSA increased by 6.6 ± 4.5%, 6.1 ± 5.1% and 2.9 ± 2.7% in the KT, HT and CT groups respectively.ConclusionsLRE in conjunction with KT or HT can provide substantial improvements in muscle strength and endurance and may be useful alternatives to traditional training practices.     

Effect of hypobaric hypoxia on auditory sensitivity

INTRODUCTION: Previous studies on the effect of hypobaric hypoxia on auditory sensitivity are not readily interpretable, in most cases because the potential effect of ambient pressure on stimulus level was not considered. In this study, auditory sensitivity to 1, 8, 12, and 16 kHz tones was compared between conditions of hypoxia and normoxia at the same simulated altitude (3700 m). METHOD: In the hypoxic condition, the partial pressure of oxygen in the inspired air was allowed to decrease with increasing altitude. In the normoxic condition, the partial pressure of oxygen was maintained at a level equivalent to that experienced at mean sea level (MSL). This comparison also controlled for any effect resulting from physiological consequences of hypobaria other than hypoxia (such as a change in middle-ear impedance). RESULTS: A small (2.57 dB) reduction in sensitivity across the frequency range tested was observed. CONCLUSION: A reduction in sensitivity of this magnitude would not be expected to have a large impact on the effectiveness of information transfer via the auditory modality.     

Impairment of rat polymorphonuclear neutrophilic granulocyte phagocytosis following repeated hypobaric hypoxia

Exposure of rats to repeated hypobaric hypoxia (17 h at 0.5 atm for 0-7 d) induced significant reduction of the phagocytic capacity of peripheral blood polymorphonuclear neutrophilic granulocytes (PMNL). In addition, the hypoxia induced a significant increase of the hematocrit, hemoglobin, thrombocyte, and total leukocyte concentrations. Differential counting of peripheral blood revealed significant granulocytosis. An increase of the concentration of corticosterone was demonstrated following 2 d of hypobaric hypoxia, whereas 5 d later the corticosterone concentrations were similar to that of the controls. The reduced PMNL phagocytic capacity observed following repeated hypobaric hypoxia may have consequences for host defence in situations of hypoxia exposure.     

高原低氧条件下经颅微电流生理训练对脑认知功能的影响

目的 研究高原低氧条件下经颅微电流生理训练对脑认知功能的影响,为高原脑认知功能的保持及训练提供技术及方法. 方法 采用经颅微电流生理训练(transcranial micro-electric current physiological training,TMCPT)对40名健康志愿者进行高原低氧条件下(海拔高度3700 m以上)的脑认知功能训练.TMCPT强度为生理级安全范围,志愿者每天训练2次(上、下午各1次),每次5 min.观察志愿者高原急进阶段(进入高原后前10 d)和高原常驻阶段(常驻1个月、常驻2个月和常驻3个月)的神经行为能力指数(neurobehavioral ability index,NAI);对其高原急进阶段和常驻阶段的睡眠质量进行评价. 结果 ①高原急进阶段:与第1天比较,训练至第10天,志愿者的数字检索能力(digital scan,DS)、记忆扫描能力(memory scan,MS)、视觉简单反应时(simple visual reaction time,SVRT)、视觉复杂反应时(complex visual reaction time,CVRT)、目标跟踪能力(pursuit aiming,PA)、连续操作能力(consecutive performance,CP)6项能力均显著增加(t=1.982～4.412,P＜0.05).②高原常驻阶段:与常驻1个月比较,常驻3个月的训练仅使6项NAI中的DS、MS、SVRT显著增加(t=3.744～5.812,P＜0.05).③睡眠质量评价:与高原急进阶段比较,经TMCPT训练的志愿者睡眠质量评定各项目分数明显降低(t=1.833～3.552,P＜0.05). 结论 经颅微电流生理训练能提高高原低氧条件下的脑认知功能和睡眠质量.可采用β频段脑波反馈训练提高脑认知能力;α频段脑波反馈训练促进睡眠.     

不同训练负荷对大鼠骨骼肌超微结构及线粒体功能的影响

 目的 研究不同训练负荷下,大鼠骨骼肌超微结构及线粒体呼吸链酶复合体Ⅰ、Ⅱ、Ⅲ、Ⅳ和总超氧化物歧化酶(total superoxide dismutase, T-SOD)、锰超氧化物歧化酶(manganese superoxide dismutase, Mn-SOD)和铜锌超氧化物歧化酶(copper zincsuperoxide dismutase, CuZn-SOD)的变化。方法 建立SD大鼠跑台训练模型,将24只大鼠随机分为正常对照组、有氧训练组、无氧训练组,每组8只,正常对照组大鼠笼内正常生活,其他两组分别进行有氧和无氧训练4周,有氧训练时采用递增负荷训练,无氧训练时采用高速训练。采用透射电镜观察骨骼肌形态及线粒体变化。用可见分光光度计检测大鼠骨骼肌线粒体呼吸链酶复合体Ⅰ、Ⅱ、Ⅲ、Ⅳ,以及T-SOD、Mn-SOD和CuZn-SOD活性。结果 相比正常对照组,电镜下有氧训练组线粒体数量增多,三联体结构明显。无氧训练组中可见大量发生肿胀的线粒体,电子密度较正常染色体低;明带与暗带界限不清,粗细肌丝排列紊乱。相比正常对照组,有氧训练组大鼠骨骼肌线粒体呼吸链酶复合体Ⅰ、Ⅱ、Ⅲ、Ⅳ,以及T-SOD、Mn-SOD和CuZn-SOD活性均显著上升(P<0.05);无氧训练组线粒体呼吸链酶复合体Ⅰ、Ⅱ、Ⅲ、Ⅳ以及T-SOD和Mn-SOD活性显著下降(P< 0.05),CuZn-SOD活性[(2.68±0.61)×10³ nkat/mgprot]与正常对照组活性值[(3.73±1.24)×10³ nkat/mgprot]相比,差异无统计学意义(P> 0.05)。结论 不同训练负荷可以改变大鼠骨骼肌线粒体功能,导致抗氧化功能发生相应变化,从而对骨骼肌形态产生较大影响。有氧训练可以改善骨骼肌形态结构和线粒体功能,减轻机体疲劳。     

缺氧或+Gz暴露对大鼠肾结石形成影响的实验研究

目的 研究低压缺氧、+Gz暴露等飞行环境因素对肾结石形成的影响. 方法 48只Wistar雄性大鼠用随机区组法分为对照组、低压缺氧组、+Gz暴露组和结石模型组,每组12只.施加相应干预因素饲养4周以后,检验各组大鼠血清生化指标:血尿素氮、血肌酐、血磷和血钙;尿液相关指标:24小时尿量、尿pH值、尿钙、尿酸和草酸含量.镜下观察大鼠肾苏木精和伊红( hematoxylin-eosin,HE)染色组织切片中结石结晶及肾小管扩张情况. 结果 ①+Gz暴露组及结石模型组大鼠血清尿素氮含量高于对照组(P＜0.05),其它指标组间差异无统计学意义.②各组大鼠24 h尿量和尿钙含量差异无统计学意义;大鼠尿液尿酸含量组间差异有统计学意义(F=33.064,P＜0.01),+Gz暴露组及结石模型组明显高于对照组(P＜0.01);尿草酸含量组间差异有统计学意义(F=4.877,P＜0.01),+Gz暴露组及结石模型组明显高于对照组(P＜0.05);各组大鼠尿pH值差异有统计学意义(F=3.555,P＜0.05),低压缺氧组大鼠尿pH值比对照组降低(P＜0.05).③对照组未见肾小管扩张及结晶体沉积;低压缺氧组未见肾小管扩张,其内可见极少量结石结晶;+Gz暴露组肾小管扩张不明显,其内可见无色透明的结石结晶;结石模型组肾小管扩张增粗,其内可见大量无色透明的结石结晶呈片状分布. 结论 +Gz暴露可能是泌尿系结石形成的危险因素之一,而低压缺氧对泌尿系结石形成的影响不明显.