Time course of individual Ca2+ sparks in frog skeletal muscle recorded at high time resolution.
Time course of individual Ca2+ sparks in frog skeletal muscle recorded at high time resolution.
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DOI：
10.1085/jgp.113.2.187
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发表时间：
1999-02
期刊：
影响因子：
--
通讯作者：
Schneider MF
中科院分区：
文献类型：
--
作者：
Lacampagne A;Ward CW;Klein MG;Schneider MF
用激光共聚焦显微镜在线扫描模式下（63 μs/行）记录单个青蛙骨骼肌纤维切割片段中的离散Ca 2+释放事件（Ca 2+“火花”）。加载有Ca 2+指示剂fluo-3的纤维在0 mV的保持电位下被电压钳位，在-90 mV下短暂地重新极化，然后用大的测试脉冲强烈地去极化以激活任何重新极化的电压传感器。使用这种高时间分辨率的系统，它是可能的记录个人的Ca 2+火花在30倍以上的时间分辨率比以前达到的。由此产生的新的实验数据提供了一种表征在火花的短暂（几毫秒）上升阶段期间荧光的时间过程的手段，这对于先前使用的每线1.5-2 ms的共焦系统是不可能的。对单个识别事件的时间过程的分析表明，荧光在火花开始时相当突然地开始上升，以稍微降低的速率继续上升到相对尖锐的峰值，然后沿着沿着准指数时间过程下降。198个火花的平均上升时间为4.7 ± 0.1 ms，上升时间与峰值幅度之间无相关性。通过在时间和空间上叠加和求和具有相似上升时间的单个火花组而构建的平均火花给出了火花的较低噪声表示，与单个事件的时间过程一致。理论上，火花的上升阶段提供了对产生火花的肌浆网Ca 2+通道释放Ca 2+离子的时间的下限估计。所观察到的荧光的时间过程表明，在火花的整个上升阶段，火花下的Ca 2+释放可以以相当恒定的速率继续，然后在峰值时相当突然地停止。
Discrete Ca2+ release events (Ca2+ “sparks”) were recorded in cut segments of single frog skeletal muscle fibers using a video-rate laser-scanning confocal microscope operating in line-scan mode (63 μs per line). Fibers loaded with the Ca2+ indicator fluo-3 were voltage clamped at a holding potential of 0 mV, briefly reprimed at −90 mV, and then strongly depolarized with a large test pulse to activate any reprimed voltage sensors. Using this high time resolution system, it was possible to record individual Ca2+ sparks at ∼30-fold higher time resolution than previously attained. The resulting new experimental data provides a means of characterizing the time course of fluorescence during the brief (a few milliseconds) rising phase of a spark, which was not possible with the previously used 1.5–2 ms per line confocal systems. Analysis of the time course of individual identified events indicates that fluorescence begins to rise rather abruptly at the start of the spark, continues to rise at a slightly decreasing rate to a relatively sharp peak, and then declines along a quasi-exponential time course. The mean rise time of 198 sparks was 4.7 ± 0.1 ms, and there was no correlation between rise time and peak amplitude. Average sparks constructed by temporally and spatially superimposing and summing groups of individual sparks having similar rise times gave a lower noise representation of the sparks, consistent with the time course of individual events. In theory, the rising phase of a spark provides a lower bound estimation of the time that Ca2+ ions are being released by the sarcoplasmic reticulum Ca2+ channel(s) generating the spark. The observed time course of fluorescence suggests that the Ca2+ release underlying a spark could continue at a fairly constant rate throughout the rising phase of the spark, and then stop rather abruptly at the time of the peak.
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影响因子：
56.9
作者：
Marx, SO;Ondrias, K;Marks, AR
通讯作者：
Marks, AR
影响因子：
3.4
作者：
Smith, GD;Keizer, JE;Cheng, HP
通讯作者：
Cheng, HP
影响因子：
56.9
作者：
CANNELL, MB;CHENG, H;LEDERER, WJ
通讯作者：
LEDERER, WJ
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
影响因子：
64.8
作者：
SCHNEIDER, MF;CHANDLER, WK
通讯作者：
CHANDLER, WK