Involvement of multiple intracellular release channels in calcium sparks of skeletal muscle
Involvement of multiple intracellular release channels in calcium sparks of skeletal muscle
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DOI：
10.1073/pnas.070056497
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发表时间：
2000-04-11
影响因子：
11.1
通讯作者：
Rios, E
中科院分区：
文献类型：
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作者：
González, A;Kirsch, WG;Rios, E
在许多类型的肌肉中，用于收缩的细胞内Ca 2+释放由短暂的Ca 2+火花组成。这是由于肌浆网中的一个还是多个通道的开放引起的尚不清楚。研究大量的火花从青蛙骨骼肌和评估其Ca2+释放电流，我们提供的证据表明，它们是由多个通道产生的。一种模式是证明在通道激活剂咖啡因的存在下，在火花上升时间的分布。这一发现与对单个通道可逆进化的预期相矛盾，但对一个群体中的通道则不然，因为群体中的通道集体可能会产生刻板的火花。释放通道激动剂imperatoxin A，ryanodine和bastadin 10引发荧光事件，开始与火花，然后衰减到稳定的水平大致成比例的单一电导的35%，50%和100%的激动剂，分别促进在双层实验。这种对应关系表明，稳定相是由一个开放通道产生的。计算的Ca2+释放电流从火花到稳定阶段衰减10至20倍，这需要在火花期间打开六个或更多个通道。
In many types of muscle, intracellular Ca2+ release for contraction consists of brief Ca2+ sparks. Whether these result from the opening of one or many channels in the sarcoplasmic reticulum is not known. Examining massive numbers of sparks from frog skeletal muscle and evaluating their Ca2+ release current, we provide evidence that they are generated by multiple channels. A mode is demonstrated in the distribution of spark rise times in the presence of the channel activator caffeine. This finding contradicts expectations for single channels evolving reversibly, but not for channels in a group, which collectively could give rise to a stereotyped spark. The release channel agonists imperatoxin A, ryanodine, and bastadin 10 elicit fluorescence events that start with a spark, then decay to steady levels roughly proportional to the unitary conductances of 35%, 50%, and 100% that the agonists, respectively, promote in bilayer experiments. This correspondence indicates that the steady phase is produced by one open channel. Calculated Ca2+ release current decays 10- to 20-fold from spark to steady phase, which requires that six or more channels be open during the spark.