Calcium and contractions of isolated smooth muscle cells from rat myometrium.
Calcium and contractions of isolated smooth muscle cells from rat myometrium.
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大鼠子宫肌层中分离的平滑肌细胞的钙和收缩。
DOI：
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发表时间：
1987
影响因子：
2.1
通讯作者：
E. Daniel
中科院分区：
文献类型：
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作者：
M. Kyozuka;J. Crankshaw;I. Berezin;S. Collins;E. Daniel
用胶原酶消化法从雌激素化的大鼠子宫肌层分离出平滑肌细胞。用丙烯醛固定后，进行电子显微镜检查和图像分割显微测量细胞长度。分离前后细胞平均长度分别为81.7微米和66.9微米。细胞的反应与等长记录的离体条的收缩相比较。分别在2 mM钙、2 mM钙+4 mM EGTA和2 mM钙+10(-8)M尼群地平溶液中观察卡巴胆碱和氯化钾的作用。卡巴胆碱和氯化钾均能使细胞缩短，且呈浓度依赖性，在加入30 S时达到最大。产生短缩所需的卡巴胆碱浓度比产生等长收缩所需的浓度低约100倍；但在钾诱导的去极化所产生的细胞缩短和等长收缩的浓度依赖关系上没有重大差异。在2 mM钙溶液中，出现时相反应，紧张性反应，使细胞最大缩短率的50%以上维持10分钟。而在2 mM Ca+4 mM EGTA或10(-8)M尼群地平中，细胞紧张性收缩在30 S后消失，细胞迅速松弛。在含EGTA的溶液中加入卡巴胆碱不同时间后，细胞启动收缩的能力呈指数下降，半衰期为160 S。加入尼群地平后，在2 mM钙溶液中去极化可使心肌细胞缩短。在2 mM Ca+4 mM EGTA溶液中，加入KCl2 mM Ca+4 mM EGTA溶液不能观察到细胞缩短，但随后加入卡巴胆碱可引起细胞缩短。这些结果表明，在无外源性钙的情况下，细胞内存在钙的储存部位，卡巴胆碱从该部位释放的钙不受去极化的影响。在分离的细胞中，没有证据表明这种收缩在无钙介质中持续存在，这与以前在小肌条上的发现是一致的，在小肌条上只获得了类似的瞬时反应。
Smooth muscle cells were isolated from estrogenized rat myometrium by collagenase digestion. Electron microscopic examination and measurement of cell lengths by image-splitting micrometry were carried out after fixation with acrolein. Mean lengths of cells before and after isolation were 81.7 and 66.9 micron, respectively. Responses of cells were compared with contractions of isolated strips recorded isometrically. Effects of carbachol and KCl were examined in 2 mM Ca, 2 mM Ca + 4 mM EGTA, and 2 mM Ca + 10(-8) M nitrendipine solution. Carbachol and KCl produced concentration-dependent shortening of isolated cells maximal at 30 s after addition. The concentrations of carbachol required to produce shortenings were about 100-fold less than those required to produce isometric contractions; but no major difference was observed in the concentration dependence of cell shortening and isometric contraction produced by potassium-induced depolarization. In 2 mM Ca solution, there was a phasic response, followed by a tonic response such that more than 50% of maximum cell shortening was maintained for 10 min. However, in 2 mM Ca + 4 mM EGTA or 10(-8) M nitrendipine, the tonic contraction was abolished and cells rapidly relaxed after 30 s. If carbachol was added to cells after varying times in the EGTA-containing solution, the ability to initiate a contraction declined exponentially with a half-time of 160 s. Effects of depolarization by KCl were examined in 2 mM Ca plus nitrendipine and 2 mM Ca + 4 mM EGTA solution. Shortening occurred in 2 mM Ca solution by depolarization but not if nitrendipine was added. Though shortening was not observed in 2 mM Ca + 4 mM EGTA solution by KCl, subsequent addition of carbachol induced shortening. These results suggested that there was an intracellular Ca store site from which Ca was released by carbachol and which was not affected by depolarization in the absence of external Ca. No evidence was obtained that the contraction persists in Ca2+-free medium in isolated cells, which is in agreement with previous findings in small muscle strips in which only a similar transient response was obtained.