Intracellular EDTA mimics parvalbumin in the promotion of skeletal muscle relaxation.
Intracellular EDTA mimics parvalbumin in the promotion of skeletal muscle relaxation.
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DOI：
10.1016/s0006-3495(99)77310-8
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发表时间：
1999-03
影响因子：
3.4
通讯作者：
J. David Johnson;Yandong Jiang;J. Rall
中科院分区：
文献类型：
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作者：
J. David Johnson;Yandong Jiang;J. Rall
小清蛋白（PA）是在一些肌肉和神经中发现的细胞内Ca 2+结合蛋白。其结合Ca 2+和促进骨骼肌松弛的能力受到其Mg 2+解离速率的限制。EDTA作为一种“人造”PA，因为它在10°C下表现出类似的Mg 2+（3s−1）和Ca 2+（0.7s−1）解离速率常数。当引入到青蛙骨骼肌，EDTA增加了10.2.7倍的松弛率，并随着破伤风持续时间的增加，EDTA失去了其能力，有助于放松（和钙螯合）在其Mg 2+的小康率。细胞内EDTA恢复其能力，有助于肌肉松弛和Ca 2+螯合在其Ca 2+解离率。与PA一样，当SR Ca-ATP酶被抑制时，EDTA对肌松和Ca 2+螯合的贡献更明显。引入EDTA到大鼠比目鱼肌，其中具有低[PA]，增加了松弛速率的方式是类似的方式，其中PA促进青蛙骨骼肌的松弛。因此，细胞内EDTA作为一个有效的模拟PA，它的使用应有助于我们了解PA的肌肉和神经的功能。
Parvalbumin (PA) is an intracellular Ca2+-binding protein found in some muscle and nerves. Its ability to bind Ca2+and facilitate skeletal muscle relaxation is limited by its Mg2+off-rate. EDTA serves as an "artificial" PA in that it exhibited similar rate constants for Mg2+(3s−1) and Ca2+(0.7s−1) dissociation at 10°C. When introduced into frog skeletal muscle, EDTA increased the relaxation rate by ∼2.7-fold, and with increasing tetanus duration, EDTA lost its ability to contribute to relaxation (and Ca2+sequestration) at its Mg2+off-rate. Intracellular EDTA recovered its ability to contribute to muscle relaxation and Ca2+sequestration at its Ca2+off-rate. Like PA, EDTA's contribution to muscle relaxation and Ca2+sequestration was more clearly observed when the SR Ca-ATPase was inhibited. Introduction of EDTA into rat soleus muscle, which has low [PA], increased the relaxation rate in a manner that was analogous to the way in which PA facilitates relaxation of frog skeletal muscle. Thus intracellular EDTA serves as an effective mimic of PA, and its use should aid in our understanding of PA's function in muscle and nerve.