The spark and its ember: separately gated local components of Ca(2+) release in skeletal muscle.
The spark and its ember: separately gated local components of Ca(2+) release in skeletal muscle.
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DOI：
10.1085/jgp.115.2.139
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发表时间：
2000-02
期刊：
影响因子：
--
通讯作者：
Ríos E
中科院分区：
文献类型：
--
作者：
González A;Kirsch WG;Shirokova N;Pizarro G;Stern MD;Ríos E
振幅，空间宽度，和上升时间的Ca 2+火花在青蛙快收缩肌肉，在三个条件下，改变激活释放通道[Ca 2 +]。对来自30个单元的总共17,000个火花进行了评价。在电压钳下的细胞中，咖啡因（0.5或1 mM）平均火花宽度增加28%，上升时间增加18%，幅度增加7%。即使在相同上升时间的事件中，宽度的增加也是显着的。自发事件记录在渗透性纤维与低内部[Mg 2 +]（0.4 mM），具有宽度和上升时间大于参考，并没有显着不同的咖啡因。参考文献中的火花平均值位于连续的荧光“脊”上，并由“脊”延续，“脊”是宽度为1 μm且振幅<0.2的延长，在100 ms内消失。咖啡因和透化细胞中不存在脊和脊。暴露的电压钳位细胞高内部[Mg 2 +]（7毫米）的影响相反，咖啡因，减少火花宽度的26%和幅度的27%。在高[Mg 2 +]，在个别火花中，可观察到持续时间和振幅可变延长至1.2。基于模拟和计算的Ca 2+释放通量平均火花，咖啡因引起的火花宽度的增加被解释为证据的半径增加的释放源，大概是通过招聘额外的通道。相反，火花变窄表明在高Mg 2+中贡献通道的损失。因此，在恒定上升时间的火花宽度的这些变化是火花的多通道起源的证据。由于嵴和余烬被Ca 2+依赖性激活的促进剂（咖啡因，低[Mg 2 +]）减少，并且在其抑制剂的存在下变得更加明显，因此它们可能是由电压传感器直接操作的Ca 2+释放的表现。
Amplitude, spatial width, and rise time of Ca2+ sparks were compared in frog fast-twitch muscle, in three conditions that alter activation of release channels by [Ca2+]. A total of ∼17,000 sparks from 30 cells were evaluated. In cells under voltage clamp, caffeine (0.5 or 1 mM) increased average spark width by 28%, rise time by 18%, and amplitude by 7%. Increases in width were significant even among events of the same rise time. Spontaneous events recorded in permeabilized fibers with low internal [Mg2+] (0.4 mM), had width and rise times greater than in reference, and not significantly different than those in caffeine. The spark average in reference rides on a continuous fluorescence “ridge” and is continued by an “ember,” a prolongation of width ∼1 μm and amplitude <0.2, vanishing in ∼100 ms. Ridge and ember were absent in caffeine and in permeabilized cells. Exposure of voltage-clamped cells to high internal [Mg2+] (7 mM) had effects opposite to caffeine, reducing spark width by 26% and amplitude by 27%. In high [Mg2+], the ember was visible in individual sparks as a prolongation of variable duration and amplitude up to 1.2. Based on simulations and calculation of Ca2+ release flux from averaged sparks, the increase in spark width caused by caffeine was interpreted as evidence of an increase in radius of the release source—presumably by recruitment of additional channels. Conversely, spark narrowing suggests loss of contributing channels in high Mg2+. Therefore, these changes in spark width at constant rise times are evidence of a multichannel origin of sparks. Because ridge and ember were reduced by promoters of Ca2+-dependent activation (caffeine, low [Mg2+]) and became more visible in the presence of its inhibitors, they are probably manifestations of Ca2+ release directly operated by voltage sensors.
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影响因子：
2.7
作者：
KUREBAYASHI, N;OGAWA, Y
通讯作者：
OGAWA, Y
影响因子：
64.8
作者：
ENDO, M;TANAKA, M;OGAWA, Y
通讯作者：
OGAWA, Y
DOI：
10.1111/j.1748-1716.1958.tb01608.x
发表时间：
1958-01-01
期刊：
ACTA PHYSIOLOGICA SCANDINAVICA
影响因子：
--
作者：
AXELSSON, J;THESLEFF, S
通讯作者：
THESLEFF, S
影响因子：
3.4
作者：
Cheng, H;Song, LS;Stern, MD
通讯作者：
Stern, MD
DOI：
10.1073/pnas.94.20.11061
发表时间：
1997-09-30
影响因子：
11.1
作者：
Klein, MG;Lacampagne, A;Schneider, MF
通讯作者：
Schneider, MF