New evidence for similarities in excitation-contraction coupling in skeletal and cardiac muscle.
New evidence for similarities in excitation-contraction coupling in skeletal and cardiac muscle.
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骨骼肌和心肌兴奋-收缩耦合相似性的新证据。
DOI：
10.1046/j.1365-201x.1998.0323e.x
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Wasserstrom,JA
中科院分区：
文献类型：
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作者：
Wasserstrom,JA
这篇综述描述了几个新的实验观察表明，一些差异，认为区分激活骨骼肌和心肌收缩，实际上可能远不如目前认为的那么深刻。特别考虑了三个这样的领域。首先，现在看来，骨骼肌中肌浆网（“Ca 2+火花”）释放Ca 2+的基本单位的激活不仅可能是电压激活的结果，而且可能是Ca 2+激活的结果，其过程非常类似于心肌中Ca 2+诱导的Ca 2+释放（CICR）。其次，有新的证据表明，心肌收缩的激活可能部分依赖于与骨骼肌相似的电压敏感释放机制（VSRM）。第三，洋地黄与心肌肌浆网Ca 2+释放通道上的高亲和力位点结合（ryanodine受体RyR）引起单通道开放概率增加，这可能有助于其正性肌力作用;尽管哺乳动物骨骼肌似乎不具有这种对强心苷的敏感性，两栖动物骨骼肌具有该通道的心脏和骨骼同种型，并且确实显示出响应洋地黄的正性变力作用。这些结果提出了一种可能性，即被认为代表两种肌肉类型之间“根本”区别的几个差异，以及它们如何产生和调节收缩，以及药理学敏感性，可能比目前认为的更相似。
This review describes several new experimental observations indicating that some of the differences thought to distinguish activation of contraction in skeletal and cardiac muscle may be in fact much less profound than are currently considered. Three such areas are considered in particular. First, it now appears that activation of the elementary units of Ca2+release from the sarcoplasmic reticulum (`Ca2+sparks') in skeletal muscle may occur not only as the result of voltage activation but also of Ca2+activation in a process very much like Ca2+‐induced Ca2+release (CICR) in cardiac muscle. Second, there is new evidence that activation of contraction in cardiac muscle may be partly reliant on a voltage‐sensitive release mechanism (VSRM) similar to that in skeletal muscle. Third, digitalis binds to a high affinity site on the cardiac sarcoplasmic reticulum Ca2+release channel (ryanodine receptor RyR) causing an increase in single channel open probability which could contribute to its positive inotropic action; although mammalian skeletal muscle does not appear to share this sensitivity to cardiac glycosides, amphibian skeletal muscle has both cardiac and skeletal isoforms of the channel and does indeed demonstrate a positive inotropic action in response to digitalis. These results raise the possibility that several differences thought to represent `fundamental' distinctions between the two muscle types and how they generate and regulate contraction, as well as pharmacological sensitivities, may be more similar than are currently considered.