MORPHOMETRIC EVALUATION OF THE CONTRACTILE APPARATUS IN PRIMARY CULTURES OF RABBIT CARDIAC MYOCYTES
MORPHOMETRIC EVALUATION OF THE CONTRACTILE APPARATUS IN PRIMARY CULTURES OF RABBIT CARDIAC MYOCYTES
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DOI：
10.1161/01.res.69.1.86
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发表时间：
1991-07-01
影响因子：
20.1
通讯作者：
DECKER, RS
中科院分区：
文献类型：
--
作者：
DECKER, ML;BEHNKEBARCLAY, M;DECKER, RS
低密度培养时，兔心肌细胞可保持静止状态1个月以上。在此期间，肌原纤维体积密度下降六倍，因为肌原纤维被分解或降解，并被肌动蛋白和α-肌动蛋白阳性、肌球蛋白阴性结构所取代，这些结构类似于肌原纤维但缺乏粗丝。这种结构被称为微小肌原纤维。这些改变的肌原纤维中肌节的长度明显小于从新鲜分离的心脏细胞或收缩的肌细胞获得的长度值。许多高密度培养物在培养的第二周出现自发的同步收缩。当跳动开始时，肌原纤维体积密度稳定，并且在接下来的培养周中没有观察到进一步下降。这种收缩的肌细胞显示出正常心脏典型的肌原纤维，没有明显的微小肌原纤维的证据。在跳动和不跳动的肌细胞中，横管系统的体积密度也显着下降，并且其降低似乎与细胞扩散的相关性比与跳动本身的相关性更密切。无法记录线粒体或肌浆网体积密度的定量变化，但肌浆网的结构组织似乎很大程度上受到心脏细胞生理状态的影响。目前的观察结果证明了机械因素在调节心肌细胞收缩装置完整性方面的重要性，并强调了培养的心脏细胞在直接研究个体心肌细胞的结构功能关系方面的实用性。
Rabbit cardiac myocytes remain quiescent for more than 1 month when cultured at low density. During this period, myofibrillar volume density declines sixfold as myofibrils are disassembled or degraded and are replaced by actin and alpha-actinin-positive, myosin-negative structures that resemble myofibrils but lack thick filaments. Such structures are termed minute myofibrils. The length of the sarcomeres in these altered myofibrils is significantly less than length values obtained from freshly isolated heart cells or from contracting myocytes. A number of high density cultures develop spontaneous, synchronous contraction during the second week of culture. Myofibrillar volume density is stabilized when beating begins, and no further decline is observed in the succeeding weeks of culture. Such contracting myocytes display myofibrils typical of normal heart with no visible evidence of minute myofibrils. The volume density of the transverse tubular system also declines significantly in both beating and nonbeating myocytes, and its reduction appears more closely correlated with cell spreading than with beating per se. No quantitative changes in volume density of mitochondria or sarcoplasmic reticulum could be documented, but the structural organization of the sarcoplasmic reticulum seems to be greatly influenced by the physiological state of the heart cell. The present observations document the importance of mechanical factors in regulating the integrity of the contractile apparatus in cardiac myocytes and emphasize the utility of the cultured heart cell to directly investigate structure-function relations in individual myocytes.