中长期模拟失重大鼠骨骼肌线粒体钙含量和肌浆网Ca^2＋—A…

为探讨失重对肌肉功能的影响，观察了中长期模拟失重时大鼠骨骼肌细胞内Ｃａｗ＾２＋转运功能变化，测定了比目鱼肌，腓肠肌线粒体钙含量和肌浆网（ＳＲ）Ｃａ＾２＋－ＡＴＰａｓｅ活性。结果是悬吊１５、３０ｄ大鼠比目鱼肌和腓肠肌线粒体Ｃａ＾＋２含量增加，肌浆网Ｃａ＾２＋－ＡＴＰ酶活性降低，说明中长期模拟失重肌细胞内Ｃａ＾２＋转运功能发生了改变，这可能是影响肌肉收缩特性的因素之一。     

耐力性运动对大鼠骨骼肌肌浆网功能的影响

大鼠以１８ｍ／ｍｉｎ的速度运动１００分钟后，测定腓肠肌和比目鱼肌肌浆网Ｃａ２＋－Ｍｇ２＋－ＡＴｐａｓｅ活性和Ｃａ２＋转运。结果发现，大鼠长时间耐力，性运动致疲劳后骨骼肌肌浆网功能下降，这一结果提示运动性骨骼肌疲劳可能与肌浆网功能下降有关。关键词：     

模拟失重大鼠心肌肌浆网Ca^2＋摄取功能的变化

为研究模拟失重对大鼠心肌肌浆网Ｃａ＾２＋摄取功能的影响，采用差速离心法制备心肌肌浆网（ＣＳＲ）精制膜，测定ＣＳＲ囊泡膜各种ＡＴＰ酶活性，并用Ｍｉｌｌｉｐｏｒｅ滤过技术测定ＣＳＲ囊泡的Ｃａ＾２＋摄取功能。结果表明，４周模拟失重大鼠心肌肌浆网膜Ｃａ＾２＋，Ｍｇ＾２＋－ＡＴＰ酶活性不变，Ｃａ＾２＋－激活ＡＴＰ酶活性却较对照组降低６．８％（Ｐ＜０．０５）。模拟失重组心肌肌浆网囊泡ＡＴＰ依赖性Ｃdisplay stat     

尾吊大鼠骨骼肌线粒体钙、镁含量和体视学的变化

为探讨尾吊大鼠骨骼肌线粒体Ｃａ２＋，Ｍｇ２＋离子含量、体视学变化与肌肉功能降低的关系，采用ＳＤ雄性大鼠５０只，体重１８０～２２０ｇ，按体重配对随机分为对照组和尾吊组。尾吊组３０只，－２５°；对照组２０只。尾吊第１５ｄ（１５只），第３０ｄ（１５只）断头，取比目鱼肌、腓肠肌冷冻待测试。采用差速离心分离线粒体，按Ｌｏｗｒｙ方法［１］测线粒体蛋白，钙、镁含量。按北京医科大学面分析方法测线粒体体视学各指标［２］。尾吊１５、３０ｄ大鼠比目鱼肌、腓肠肌线粒体Ｃａ、Ｍｇ含量与对照比增加，体视学各指标均有不同程度的改变。结果表明，尾吊后大鼠骨骼肌线粒体Ｃａ、Ｍｇ离子代谢和体视学均发生改变，其变化必然影响肌肉收缩功能。     

急性运动对骨骼肌肌浆网钙转运功能的影响

肌浆网（ＳＲ）在调节骨骼肌收缩一舒张过程中发挥重要作用。我们在本研究中采用持续运动方式观察急性运动对ＳＲ钙转运能力的影响，发现运动后股四头肌ＳＲＣａ２＋－Ｍｇｚ＋－ＡＴＰａｓｅ水解活性下降１８．３１％（Ｐ＜０．０１），ＳＲＣａ２＋－ＡＴＰａｓｅ水解活性下降１８．４７％（Ｐ＜０．０１）；ＳＲＣａ２＋转运能力明显下降，表现为ＳＲＣａ２＋初始摄取率和ＳＲＣａ２＋最大转运能力分别下降５７．７９％（Ｐ＜０．０１）和５５．９８％（Ｐ＜０．０１）。本研究结果提示急性运动后ＳＲＣａ２＋摄取功能下降可能与运动性骨骼肌疲劳密切相关。     

模拟失重可能降低大鼠心肌肌浆网功能

采用离体乳头肌灌流、改变刺激频率和快速冷却等干预实验，探讨模拟失重４周大鼠心肌收缩性能降低的可能机理。结果表明：模拟失重大鼠乳头肌：（１）等长收缩达到张力峰值的时间明显延长；（２）细胞外Ｃａ＋浓度为８．０ｍｍｏｌ／Ｌ时，增加刺激频率，张力随之降低；（３）电刺激张力与停止电刺激ｌｓ的冷挛缩张力明显降低。这些均提示，模拟失重４周可能使心肌肌浆网Ｃａ＋＋摄取与释放速率降低。     

血管紧张素系统在烧伤后心肌损害及心功能障碍中的作用

目的观察心肌局部肾素－血管紧张素系统（ＲＡＳ）在烧伤早期心肌损害及心功能障碍中的作用。方法测定烧伤前（对照组）及烧伤后３,８,２４小时左心功能变化、血浆心肌球蛋白轻链１（ＣＭＬＣ１）含量、心肌血管紧张素转换酶（ＡＣＥ）活性、血管紧张素Ⅱ（Ａｎ）及钙离子（Ｃａ２＋）含量,测定心肌肌浆网（ＳＲ）Ｃａ２＋－ＡＴＰａｓｅ活性及ＳＲＣａ２＋转运功能。结果烧伤大鼠左心室收缩功能明显降低,ＣＭＬＣ１显著升高,心肌ＡＣＥ活性、Ａｎ及Ｃａ２＋含量增加,ＳＲＣａ２＋－ＡＴＰａｓｅ活性降低,ＳＲ　Ｃａ２＋摄取减少。预防性给予ＡＣＥ抑制剂可显著降低烧伤后心肌ＡＣＥ活性,减少Ａ。产生,使血浆ＣＭＬＣ１下降、Ｃａ２＋含量降低,增加ＳＲＣａ２＋－ＡＴＰａｓｅ活性、ＳＲＣａ２＋摄取,明显改善左心室功能。结论心肌局部ＲＡＳ激活参与烧伤后心肌损伤,抑制ＳＲＣａ２＋转运可能是其促进心功能障碍的机制之一。     

模拟失重下机体的整体调节

大鼠悬吊１５ｄ和３０ｄ，同体同步采样进行多系统多指标观察模拟失重时的生理功能发迹结果表明：出现矿盐含量减少、组织上地肌和腓肠肌Ｃａ＾２＋转运动能发迹及红细胞变形性降低的同时，局部因子和全身性调节因子亦同步出现抑制现象，说明模拟失重时生理功能有着复杂的局部和整体调节过程。     

冷冻伤性脑水肿的发生机制及尼莫地平治疗作用的实验研究

目的研究大鼠冷冻伤性脑水肿不同时间脑组织伊文思兰（ＥＢ）、突触体内［Ｃａ２＋］ｉ及Ｃａ２＋－ＡＴＰ酶活性变化与脑含水量变化之间的规律，以探讨冷冻伤性脑水肿的发生机制和类型。方法干湿法测定脑组织水分含量，甲酰胺法测定ＥＢ含量，Ｆｕｒａ－２／ＡＭ荧光标记法测定突触体内［Ｃａ２＋］ｉ，微量定磷法测定线粒体Ｃａ２＋－ＡＴＰ酶活性。采用尼莫地平进行治疗，研究其对ＥＢ含量、［Ｃａ２＋］ｉ、Ｃａ２＋－ＡＴＰ酶活性和脑水肿的影响。结果冷冻伤后３０分钟即已发生Ｃａ２＋超载，伴随Ｃａ２＋－ＡＴＰ酶活性下降及脑组织水分含量及ＥＢ含量增加。尼莫地平治疗后ＥＢ含量和［Ｃａ２＋］ｉ明显下降，而Ｃａ２＋－ＡＴＰ酶活性明显恢复，脑水肿明显减轻。结论ＢＢＢ的通透性增加和细胞内钙通道开放，钙离子浓度超载在脑水肿的发生与发展过程中起了重要作用。冷冻伤性脑水肿在早期既有细胞毒性脑水肿，又有血管源性脑水肿，即混合性脑水肿。     

悬吊模拟失重对大鼠比目鱼肌纤维肌力、硬度和钙离子敏感性的影响

悬吊模拟失重对大鼠比目鱼肌纤维肌力、硬度和钙离子敏感性的影响失重或悬吊模拟失重（ＨＵ）条件下，大鼠比目鱼肌（ＳＯＬ）发生明显的萎缩，同时肌肉力学特征也降低，表现为纤维肌力、单位面积（ＣＳＡ）最大肌力和最大张力（Ｐ０）的降低。肌力和张力与ＣＳＡ横桥结合...     

低氧习服对大鼠心肌肌浆网酶活性和钙摄取能力的影响

目的 研究低氧习服对大鼠心肌功能的影响。方法 18只雄性Wistar大鼠,随机分为常氧对照组、急性低氧组和间断低氧习服组3组,每组n=6。经间断低氧习服（先后模拟海拔3000m和5000m低氧各14d,每天4h,最后8000m低氧4h）和急性低氧（模拟海拔8000m低氧4h）的大鼠,断头处死,迅速取出心脏,分离心肌浆网SR,用水解磷酸根法测定ATP酶活性,用γ-32Pi参入法测定PLB的磷酸化,用微孔滤膜过滤技术测定ATP依赖性心肌SR^45Ca^2＋摄取功能。结果 1）低氧对大鼠心肌SRNa^＋,K^＋-ATPase的活性无明显影响;2）急性低氧大鼠心肌SRCa^2＋,Mg^2＋-ATPase活性较正常大鼠显著降低（P〈0．01）,而低氧习服大鼠心肌SRCa^2＋,Mg^2＋-ATPase活性则较未习服者明显为高（P〈0．01）,接近正常水平;3）急性低氧大鼠心肌SRPLB的磷酸化显著减弱,而低氧习服大鼠PLB的磷酸化则明显提高,表明低氧习服可减轻对钙泵的抑制;4）急性低氧可显著抑制心肌SR对^45Ca^2＋的摄取,而低氧习服时,SR摄取^45Ca^2＋的能力显著增强,最大摄取量显著增高。结论 低氧习服可以明显提高心肌SRCa^2＋,Mg^2＋-ATPase及钙泵的活性,从而提高心肌收缩和舒张功能。     

骨骼肌条肌质网Ca~(2+)释放功能的间接测量方法

目的本实验拟建立测量骨骼肌肌质网(SR)钙离子释放功能的简便方法。方法分析大鼠离体比目鱼肌肌条间断强直收缩张力峰值到75%恢复的时间(TR75),TR75呈先延长然后缓慢缩短。以延长至最大时的TR75除以第一次强直收缩的TR75,获得TR75延长比值(R-TR75)。结果增加刺激电压或用5mmoL/L Caffeine灌流(增加SR Ca2+释放通道开放几率)比目鱼肌肌条,R-TR75从对照组的2.5倍均增加到3.0倍。相反,5 mmol/L硫酸镁灌流抑制SR Ca2+释放通道,使R-TR75明显减小。间隔60 min的2次间断强直疲劳收缩,其R-TR75间无明显差别,但间隔5或10 min,再次进行间断强直疲劳收缩期间的R-TR75呈显著减小。萎缩比目鱼肌间断强直疲劳收缩期间,R-TR75增加2.9倍,明显高于对照组。结论比目鱼肌肌条间断强直疲劳收缩期间,在肌质网Ca2+-ATP酶活性没有改变的条件下,TR75延长比值可间接反映SR钙释放功能。另外,去负荷2周萎缩比目鱼肌的R-TR75增加提示其SR钙释放功能可能增强。     

Effects of a 21-day expedition to 6,194 m on human skeletal muscle SR Ca2+-ATPase

We investigated the effects of a 21-day expedition to the summit of Mount Denali, Alaska (6,194 m) on selected Ca2+ sequestration properties of sarcoplasmic reticulum (SR) calcium pump in vastus lateralis muscle. Muscle samples were obtained by biopsy from 5 male climbers (peak oxygen consumption, VO2peak = 52.3 +/- 2.1 mL.kg(-1).min(-1)) approximately 7 days prior to (PRE) and 4 days following (POST) the expedition. A comparison of PRE versus POST measures of maximal Ca2+-ATPase activities (117 +/- 8.5 vs. 97.6 +/- 5.6 nmol.mg protein(-1).min(-1)) and Ca2+-uptake (204 +/- 15 vs. 161 +/- 11 nmol.mg protein(-1).min(-1)) measured in crude homogenates obtained from pre-exercised muscle, indicated only an effect (p < 0.05) of the expedition on Ca2+-uptake. The reduction in Ca2+-ATPase activity, representing 16.6%, was not significant (p = 0.089). The sarco endoplasmic reticulum calcium (SERCA)-ATPase isoforms, measured using Western blotting techniques, revealed a small reduction (p < 0.05) in SERCA 1 (-4.6 +/- 1.9%), but not in SERCA 2a (+2.0 +/- 1.4%). Prior to the expedition, both Ca2+-ATPase activity and Ca2+-uptake were reduced (p < 0.05) by approximately 34 and 18%, respectively, following 40 min of a two-step continuous cycling task (20 min at 59% VO2peak and 20 min at 74% VO2peak). The exercise-induced reduction in Ca2+-ATPase activity was independent of fiber type. Only in the case of Ca2+-uptake was a lower exercise response (p < 0.05) observed following the expedition, an effect that was due to the lower resting value. It is concluded that acclimatization as experienced during a mountaineering expedition induces changes in the properties of the SR Ca2+-pump, and particularly to Ca2+-sequestering function.     

Training-induced sarcoplasmic reticulum Ca2+ unloading occurs without Ca2+ influx

INTRODUCTION: Aerobic exercise training elicits adaptations in coronary smooth muscle that result in a novel intracellular Ca2+ signaling phenomenon termed sarcoplasmic reticulum (SR) Ca2+ unloading. Sarcoplasmic reticulum Ca2+ unloading is defined as a time-dependent depletion and then repletion of the caffeine-sensitive SR Ca2+ store. PURPOSE: To determine whether Ca2+ influx is necessary to elicit SR Ca2+ unloading. METHODS: Male, Yucatan swine (8 months old) were maintained: 1) sedentary or 2) exercise trained (treadmill running performed 5 d.wk(-1) for 16 wk). Smooth muscle cells were isolated from the right coronary artery and loaded with the intracellular Ca2+-indicator, fura-2. Sarcoplasmic reticulum Ca2+ content was assessed as the change in the caffeine (5 mM)-induced intracellular Ca2+ peak after a 2-, 5-, 8-, 11- or 13-min recovery from high K+ (depolarization)-induced Ca2+ influx in a physiological (2 mM) Ca2+ solution. The effect of Ca2+ influx on SR Ca2+ unloading was assessed by replacing the 2 mM Ca2+ solution with a virtually Ca2+-free (100 nM) solution during the recovery period. RESULTS: Consistent with previous studies, SR Ca2+ unloading was not observed in cells from sedentary swine. In cells from exercise-trained swine, SR Ca2+ depletion was observed in both the 2 mM and Ca2+-free solutions, suggesting that Ca2+-induced Ca2+ release was not initiating SR Ca2+ unloading during the recovery period. In addition, the reloading of the SR Ca2+ store occurred even in the Ca2+-free solution, suggesting that exercise training facilitates an internal cycling of Ca2+ between the SR and another intracellular Ca2+ store. CONCLUSION: In coronary smooth muscle from male swine, Ca2+ influx is not necessary for the exercise training-induced phenomenon, SR Ca2+ unloading.     

抑制SERCA活性减缓萎缩比目鱼肌间断强直收缩张力的下降(英文)

目的确定骨骼肌收缩的舒张时程可作为判断肌质网钙离子ATP酶(SERCA)活性的功能性指标,并探讨SERCA活性对后肢去负荷大鼠萎缩比目鱼肌间断强直收缩张力下降速率的调节作用。方法采用尾部悬吊大鼠模型,游离骨骼肌肌条进行灌流,观测收缩功能的改变。结果与对照组相比,去负荷4周萎缩比目鱼肌肌条在27℃灌流条件下,间断强直收缩的舒张时程(TR75)显著缩短,强直收缩张力快速下降。相反,采用SERCA活性抑制剂环匹阿尼酸(Cyclopiazonic Acid),可延长TR75时程,并恢复强直收缩张力下降速率至对照水平。较低灌流温度(22℃)降低对照大鼠比目鱼肌SERCA活性,同时减缓强直收缩张力的下降;较高温度(35℃)则产生相反的结果。低浓度咖啡因灌流不能改变萎缩比目鱼肌强直收缩下降速率;增加灌流液Ca2+浓度和钙离子载体A23187作用下,减慢强直收缩张力下降速率。结论缩短的TR75与萎缩比目鱼肌SERCA活性增加相关联,TR75可作为表征SERCA活性的功能性指标。适度抑制SERCA活性,可能通过提高肌纤维内Ca2+浓度,减缓强直收缩张力下降速率。     

脑复合剂对脑损伤大鼠Na+-K+-ATP酶、Ca2+-ATP酶活性及Ca2+调控的影响

目的 观察刨伤性脑损伤(traumatic brain injury,TBI)大鼠脑组织匀浆及线粒体Na+-K+-ATP酶、Ca2+-ATP酶活性、神经细胞内游离Ca2+浓度及脑组织钙调蛋白(CaM)表达的动态变化,探讨脑复合剂脑保护作用的分子生物学机制.方法 建立大鼠TBI模型,分别设立假手术组、TBI组及中药治疗组.中药治疗组给予脑复合剂10 g·kg-1·d-1,假手术组及TBI组给予同等剂量等渗盐水,2次/d,连续7 d.分别于TBI后24 h、72 h、1周等3个时相点处死大鼠,动态定量分析各组大鼠脑组织匀浆及线粒体Na+-K+-ATP酶、Ca2+-ATP酶活性、神经细胞内游离Ca2+浓度及脑组织CaM表达的变化.结果 TBI组各时相点大鼠脑组织匀浆及线粒体Na+-K+-ATP酶、Ca2+-ATP酶活性均明显降低,于TBI后72 h后逐渐恢复,1周时仍明显低于假手术组.中药治疗组大鼠脑组织Na+-K+-ATP酶、Ca2+-ATP酶活性显著增加(P＜0.05);TBI组各时相大鼠脑组织神经细胞内游离Ca2+浓度及脑组织CaM表达均有不同程度增高,于伤后24 h达高峰,持续至72 h仍高于假手术组.而中药治疗组各时相大鼠神经细胞内游离Ca2+浓度及脑组织CaM表达明显低于TBI组(P＜0.05).结论 脑复合剂的脑保护作用可能与增加脑组织Na+-K+-ATP酶、Ca2+-ATP酶的活性,从而减轻TBI后脑细胞的能量代谢障碍,降低神经细胞内游离Ca2+浓度及脑组织CaM表达,减轻Ca2+超载所导致的继发性脑损伤有关.     

Effect of tail suspension on mitochondrial Ca2+ and Mg2+ and parameters of electron microscopic morphometry in rats' skeletal muscle]

Changes of mitochondrial Ca2+, mitochondrial Mg2+ and parameters of electron microscopic morphometry in rats' skeletal muscle after 15 or 30 d tail suspension were observed. The results showed that mitochondrial Ca2+ [correction of Ma2+] mitochondrial Mg2+ increased and morphometry of mitochondrial in skeletal muscle showed that volume density (Vv), surface density (Sv), numerical density (Nv) increased. Mean volume (V) decreased. Specific surface increased in soleus muscle, while that parameter remain unchanged in gastrocnemus musles. It suggests that these changes may be denoted to the decrease of muscular contractive function in simulated weightlessness.     

Ca2+ transport across the plasma membrane of striated muscle

In both types of striated muscle (skeletal and cardiac), calcium flux across the plasma membrane (sarcolemma) is regulated by at least three distinct membrane proteins; a voltage-dependent Ca2+ channel, Ca2+ pump (Ca2+ ATPase), and the Na+/Ca2+ antiporter. Each of these proteins is subject to regulation by intracellular second messengers. The magnitude and the role of this transsarcolemmal calcium flux are quite different between cardiac and skeletal muscle. In cardiac muscle, the influx is large, precedes, and is obligatory for contraction. There is general agreement that this influx is the trigger for Ca2+ release from the sarcoplasmic reticulum (SR) in the heart according to the Ca2+-induced Ca2+ release hypothesis. Variations in the transsarcolemmal Ca2+ influx have a profound effect on the strength of cardiac contraction, and it appears that this is the primary physiological strategy for regulation of contractility. In skeletal muscle, on the other hand, the T-tubules represent the richest source of dihydropyridine (DHP)-sensitive calcium channels known to exist, yet the influx of Ca2+ is proportionally much smaller and a significant portion enters the fiber following the twitch. While the majority of the Ca2+ influx is twitch dependent, it is quite clear that contraction in skeletal muscle is not predicated on this influx. It has been proposed that these DHP channels act as voltage sensors in order to initiate release of SR Ca2+; however, the link between the sensors and the opening of the SR Ca2+ (ryanodine-sensitive) channel is unknown. Transsarcolemmal Ca2+ transport appears to be subject to intense regulation to modify the acute response and demonstrates some plasticity in the adaptation to chronic perturbations.     

Simultaneous multicompartment intracellular Ca2+ measurements in the perfused heart using 19F NMR spectroscopy

Although Ca²⁺ transport regulation at subcellular organelles is of great interest, only limited methodology has been available for measuring organellar [Ca²⁺] levels. The present study employs the ¹⁹F NMR resonance frequency of 4F-BAPTA to measure free [Ca²⁺]. In 4F-BAPTA loaded perfused rabbit hearts, two ¹⁹F NMR resonances were clearly observed. The frequency of one was consistent with cytosolic [Ca²⁺] levels. Responses to agents that alter sarcoplasmic reticulum function identified the other resonance as originating from that organelle. The experiments demonstrate the utility of NMR shift indicator methodology in obtaining simultaneous multi-compartment intracellular [Ca²⁺] measurements and in enabling organellar [Ca²⁺] measurements to be made from within intact living tissue.