骨骼肌兴奋收缩偶联时肌浆网内Ca2+释放的形态-功能变化研究

采用双向红外线探测器－计算机控制的电刺激－超低温快速冷冻固定同步技术,透射电子显微镜,X－射线能量色散谱及Ca^2 细胞化学技术,从超微结构形态学角度,实时研究并获取骨骼肌兴历－收缩偶联时,肌浆网内Ca^2 释放及肌浆网的形态改变。研究表明：1．骨骼肌组织在收缩潜伏期内,肌浆网膜与T－管膜接触。2．在潜伏期（＜10ms)内,肌浆网内的钙离浓度随时间经历的延长而减少。3．骨骼肌组织在收缩潜伏期开始0．8ms时,在T－管外周围（纳米处）,有Ca2 分 ,丰,可以认为骨骼肌兴奋收缩偶联时,T－管外存在Ca^2 结合位点。     

骨骼肌收缩潜伏期内肌浆网Ca2+的定量定位研究

本文报道了采用红外探测-计算机控制的超低温快速冷冻固定技术、X-射线能量色散谱微区定量分析及Ca2+细胞化学技术对骨骼肌收缩潜伏期内肌浆网内的Ca2+进行了分析,从超微结构形态学的角度对骨骼肌兴奋-收缩偶联发生时,Ca2+的作用进行了研究,这对揭示骨骼肌兴奋-收缩偶联时,肌浆网内Ca2+的释放机理研究有重要意义.     

肌兴奋收缩偶联时肌浆网的超微结构研究

骨骼肌兴奋-收缩偶联由于其明显的理论和临床意义、更由于其对运动医学及军事医学的进展有重要影响而一直受到关注，但骨骼肌兴奋收缩偶联时肌浆网膜上Ca^2＋释放通道如何使肌浆网内的Ca^2＋释放一直是困扰学术界的难题。由于骨骼肌兴奋收缩偶联发生的时间历程极短（以毫秒计），更由于肌浆网膜上Ca^2＋释放通道蛋白极易被化学固定所破坏，常规化学固定（固定时间以分钟计）无法保留其瞬间经历时的超微结构形态变化，因而很难对其进行形态上的观察及证明。我们采用低温冷冻技术、计算机控制的毫秒级实时处理技术对潜伏期内骨骼肌结构变化进行固定，采用透射电镜观察骨骼肌肌浆网、T-管在收缩潜伏期内超微结构的时相-结构变化。     

骨骼肌兴奋收缩偶联时肌浆网膜Ca2+通道的研究

目的：从毫秒级功能变化水平实时观察骨骼肌肌浆网、T-管在收缩潜伏期内超微结构的时相—形态变化。方法：采用双红外线探测器—计算机控制的电刺激—超低温快速冷冻固定同步技术,对电刺激后的蟾蜍骨骼肌组织作快速冷冻固定,采用透射电镜对骨骼肌在电刺激后0．8ms,2ms,4．6ms,10．8ms和18．4ms的超微结构变化进行观察。结果：刺激0．8ms后,肌浆网和T-管未见明显改变。刺激2ms后,SR内出现电子密度较大的物质。刺激4．6ms后,肌浆网膜内外侧可见一一对应的电子密度大的物质。刺激10．8ms后,SR与T-管形态又恢复原状,SR内电子密度大的物质消失。结论：骨骼肌兴奋-收缩偶联发生时,肌浆网的形态发生改变,肌浆网内出现电子密度较大的物质且逐渐向靠近T-管的方向移动。     

骨骼肌在兴奋收缩偶联潜伏期内毫秒级功能变化时的形态研究

骨骼肌在兴奋收缩偶联潜伏期内毫秒级功能变化时的形态研究杨勇骥郑尊邵晓良夏金辉余宏宇姜永良宋田斌吴越（第二军医大学基础部生物物理研究所，上海２００４３３）采用双向红外线探测器—计算机控制的电刺激与超低温快速冷冻固定同步技术对骨骼肌组织电刺激后，在潜伏期...     

心肌组织T-管结构的扫描电镜研究

心肌兴奋 收缩偶联由于其明显的理论和临床意义一直受到关注。肌浆网 (ｓａｒｃｏｐｌａｓｍｉｃｒｅｔｉｃｕｌｕｍＳＲ)及肌浆网内Ｃａ2 +释放在心肌兴奋 收缩偶联机制中起着重要作用。在肌兴奋 收缩偶联机制中起重要作用的单元为三联管即Ｔ 管、肌浆网。由透射电镜观察得出 ,Ｔ 管是肌细胞膜凹陷垂直伸向细胞浆的横管。我们采用扫描电镜对心肌纤维与Ｔ 管的关系进行了研究 ,取得了有意义的结果。材料与方法正常豚鼠 (体重 30 0ｇ,由第二军医大学动物中心提供 ) ,颈椎脱位。取其心室部位的心肌组织 ,用玻璃分针小心的将心组织分离为长约 …     

骨骼肌兴奋收缩偶联时钙诱导钙释放机理的研究

近年来 ,国外学者由生理学实验发现 ,在骨骼肌兴奋 -收缩偶联过程中 ,不仅存在 DCT假说 ,还存在钙诱导钙释放 ( Calcium Induced Calcium Release,简称 CICR)假说 (该假说一般用于解释心肌兴奋 -收缩偶联时 ,肌浆网内的 Ca2 + 释放机理 )。但因肌组织 (包括骨骼肌与心肌 )兴奋 -收缩偶联发生时的变化时间极快 ,达到毫秒级水平 ,因此目前常规化学固定 (固定时间以分钟计 )制样法无法保留肌组织兴奋 -收缩偶联发生瞬间时的超微结构形态及离子 (包括 Ca2 + ,Na+ ,K+ 等 )浓度的变化。我们采用双向红外线探测器 -计算机控制的电刺激与超低…     

骨骼肌兴奋收缩偶联时肌膜下小泡的超微结构变化

目的：从毫秒级功能变化水平实时观察骨骼肌肌膜下小泡在收缩潜伏期内的时相-形态变化。方法：采用双红外线探测器-计算机控制的电刺激-超低温快速冷冻固定同步技术,对电刺激后的蟾蜍骨骼肌组织作快速冷冻固定,冷冻置换,微波浸透包埋和超薄切片,在透射电镜下观察该骨骼肌细胞在电刺激后0．0ms,4．6ms,24ms的超微结构变化。结果：未加刺激的骨骼肌细胞的肌膜下仅见少量小泡分布;施加刺激4．6ms后肌膜下出现大量小泡,并由3～8个小泡融合成聚合体;24ms后小泡急剧减少,仅残留少量小泡紧靠肌膜下。结论：骨骼肌兴奋．收缩偶联发生时,肌膜下出现大量小泡。     

计算机控制的电刺激-超低温快速冷冻固定同步的研究

本文报道了以红外线技术和计算机控制的电刺激 -超低温快速冷冻固定同步技术 ,研究骨骼肌组织被电刺激后 ,与骨骼肌组织的生理变化 (即兴奋 -收缩偶联发生的瞬间 )同步 ,在骨骼肌组织结构发生变化的同时 ,对其超低温快速冷冻固定 ,从毫秒级变化的水平获得骨骼肌组织在兴奋-收缩偶联发生时的细胞超微结构形态变化。材料与方法　双向红外探测器由两对透射型红外光电开关管及相应的信号处理及脉冲整形输出线路构成。透射型红外光电开关管的响应时间小于 1 0 μs,可满足毫秒级分析要求。脉冲整形输出线路将透射型红外光电开关管接收的信号转换成…     

电刺激—冷冻固定法研究兴奋收缩偶联时骨骼肌的超微结构形态变化

兴奋－收缩偶联时，肌浆网中的钙离子是通过何种途径被刺激而释放的？偶联发生时期形态变化与其功能变化存在着什么的关系？这是细胞生物学、生理学几十年来最感兴趣的研究热点之一。     

Novel muscle spindles containing muscle fibers devoid of sensory innervation in the extensor digitorum longus muscle of aged rats

We examined the structural features of muscle spindles at the equatorial and juxtaequatorial regions in the extensor digitorum longus muscle of adult (12 months) and aged (25 months) rats. In aged muscle spindles, the lamellated layers of the spindle capsule were a little increased in number compared to those in the adult ones. Two novel muscle spindles were observed in the aged muscle. In one muscle spindle, the spindle capsule contained four thin intrafusal muscle fibers invested by the inner capsule and two muscle fibers between the layers of the spindle capsule. Serial semithin sections revealed that the latter lacked the investment of the spindle capsule at the polar region. The other muscle spindle contained four intrafusal muscle fibers: two thin sensory-innervated muscle fibers invested by the inner capsule and two thick muscle fibers similar in structural features to neighboring extrafusal muscle fibers and lacking sensory innervation within the wide periaxial space. These findings suggest that two muscle fibers between the layers of the spindle capsule may be invested by the newly formed capsular cells during aging, while two thick fibers within the periaxial space may fail to receive the sensory innervation during the early development and follow the course of extrafusal fiber differentiation.     

The sensory region of muscle spindles in the posterior cricoarytenoid muscle of the marmoset

We examined muscle spindles in the posterior cricoarytenoid (PCA) muscle of the marmoset. The spindle capsule contained only one intrafusal muscle fiber which did not form a typical aggregation of equatorial nuclei such as bags and chains. The intrafusal fiber was innervated by sensory endings which branched and arranged irregularly. These sensory endings lay on the surface of the fiber in shallow grooves or deeply penetrated into it. These findings suggest that the muscle spindles in the marmoset PCA muscle are strikingly different in the structure of intrafusal fibers in the arrangement of sensory endings from those in common mammalian skeletal muscles.     

Regeneration of muscle fibers in the extensor digitorum longus muscle of the aged rat

Regeneration of muscle fibers was observed in the extensor digitorum longus (EDL) muscle of aged (24 and 27 months) Wistar rats. The aged muscles consisted almost exclusively of medium-sized muscle fibers. In addition to degenerating and/or atrophied muscle fibers, very small muscle fibers <10 mum in diameter were observed in some muscle bundles which sporadically distributed in the muscle. In the degenerating muscle fibers, satellite cells mostly appeared to be normal, possibly surviving within the scaffold of basal lamina to form new (regenerating) muscle fibers. However, some of the satellite cells were degenerated and destroyed, suggesting the decrease in number of muscle fibers. On the other hand, very small muscle fibers existed between small and/or medium-sized muscle fibers or in the wide interstitial spaces between them solitarily or in small groups. In addition, immature muscle cells having a centrally located nucleus and sporadically distributed myofilaments were observed among the small and/or medium-sized muscle fibers and partially lacked a layer of basal lamina. These immature muscle cells were often closely apposed to fibroblasts with some slender cytoplasmic processes and/or to each other without an interposing basal lamina. These findings suggest that in addition to satellite cells within the basal lamina tubes, some of the regenerating muscle fibers in the aged EDL muscle may be originated from mesenchymal cells such as fibroblasts in the interstitial spaces.     

犬钢珠伤和正常肌肉光学性质的比较

本实验研究表明,犬钢珠枪伤和正常肌肉的光学性质存在着明显的差异,这些差异可作为大钢珠枪伤肌肉坏死界线的判定,因此具有临床应用价值.     

Fine structural study of the regeneration of muscle fibers in the rat soleus muscle during aging

We examined the regeneration of muscle fibers in the soleus muscle of mature (12 months) and aged (24 and 27 months) rats by using electron microscopy. In both mature and aged muscles, regenerating muscle fibers were mainly formed within the scaffolds of basal laminae after necrosis. In the aged muscle, however, satellite cells within the scaffolds were occasionally destroyed, and immature muscle cells occurred in and around muscle bundles. These findings suggest that new muscle fibers formed in the interstitial spaces may contribute to the total number of regenerated muscle fibers. The origin of the immature muscle cells is briefly discussed.     

A comparison of static and dynamic characteristics between rectuseye muscle and linear muscle model predictions

The characteristics of a muscle model are analyzed using rectus eye muscle parameter values and compared to rectus eye muscle data. The muscle is modeled as a viscoelastic parallel combination connected to a parallel combination of active state tension generator, viscosity element, and length tension elastic element. Each of the elements is linear and their existence is supported with physiological evidence. The static and dynamic properties of the muscle model are compared to rectus eye muscle data. The length-tension characteristics of the model are in good agreement with the data within the operating region of the muscle. With the muscle model incorporated into a lever system to match the isotonic experiment paradigm, simulation results for this linear system yield a nonlinear force-velocity curve. Moreover, the family of force-velocity curves generated with different stimulus rates reported in the literature match the predictions of the model without parametric changes. The results of this paper are important in studies involving the oculomotor plant and oculomotor neural networks. Additionally, these results may be applicable to other muscles.     

A novel nerve bundle containing thin muscle fibers in the posterior cricoarytenoid muscle of the marmoset

We examined a novel nerve bundle in the posterior cricoarytenoid muscle of the marmoset. This intramuscular nerve bundle contained two thin muscle fibers about 10 microm in diameter, like intrafusal muscle fibers in the muscle spindle. These thin muscle fibers were individually surrounded by nerve bundles consisting of numerous nonmyelinated nerve fibers. Individual nerve axons contained clear synaptic vesicles and large granulated vesicles, being possibly cholinergic (parasympathetic) in nature. These nerve axons were often in contact with the muscle fiber with and without an interposing basal lamina. Two thin muscle fibers gradually terminated in the endoneural connective tissue around myelinated and nonmyelinated nerve fibers during their course. The innervation of thin muscle fibers in the novel nerve bundle is briefly discussed.     

Proportional electromyogram-controlled demand muscle stimulator

A myoelectric-controlled stimulator that can sense biopotentials and deliver stimulus pulses to the patient through the same electrodes using time-sharing techniques is described. The stimulus is produced only when demanded, and its amplitude is proportional to the contraction causing this demand.     

Remodelling of capillary networks around muscle fibres in the extensor digitorum longus muscle of the normal aged rat

Structural changes of capillaries around muscle fibres following their degeneration and regeneration were further examined in the extensor digitorum longus muscle of the 24-month-old normal rat. Bundles of muscle fibres were divided into three types: muscle bundles consisting of large muscle fibres exclusively more than 35 microm in diameter (type 1), various-sized muscle fibres ranging from 10 to 60 microm in diameter (type 2) and only small muscle fibres 20-40 microm in diameter (type 3). The mean number of capillaries around a muscle fibre was extremely high in the type 3 muscle bundle (4.83) and much lower in the type 2 muscle bundle (2.72) compared with that in the type 1 muscle bundle (3.48). Capillaries in the type 1 muscle bundle were round or oval in shape and were of the continuous type. In the type 2 muscle bundle, capillaries around large degenerating muscle fibres showed an irregularly compressed shape and the scaffolds of basal laminae were often found around them, being a result of the destruction of capillaries. On the other hand, small-sized capillaries less than 5 microm in diameter, being possibly regenerating capillaries, were found around small (probably regenerating) muscle fibres and often had a small number (less than 10) of fenestrae. Capillaries in the type 3 muscle bundle, similar in shape and size to those in the type 1, frequently branched or joined, but some of them were partially destroyed. These findings suggest that capillaries degenerate and regenerate to remodel capillary networks around the muscle fibres following their degeneration and regeneration, and that to effectively supply oxygen and nutrients to regenerating muscle fibres, capillaries temporarily form fenestrae and then the capillary networks become dense by sprouts from the existing capillaries, but excess capillaries may be gradually destroyed following maturation of the muscle fibres.