大鼠心室肌细胞中钙火花期间钙释放的终止。
Termination of Ca2+ release during Ca2+ sparks in rat ventricular myocytes.
作者信息
Lukyanenko V, Wiesner T F, Gyorke S
机构信息
Department of Physiology, Texas Tech University Health Science Center, Lubbock, TX 79430, USA.
出版信息
J Physiol. 1998 Mar 15;507 ( Pt 3)(Pt 3):667-77. doi: 10.1111/j.1469-7793.1998.667bs.x.
Abstract
- Confocal Ca2+ imaging was used to measure spontaneous release events (Ca2+ sparks) in fluo-3-loaded isolated rat ventricular myocytes. 2. The microscopic Ca2+ release flux underlying Ca2+ sparks was derived by adapting the methods used previously to describe macroscopic Ca2+ release from cell-averaged Ca2+ transients. 3. The magnitude of the local release fluxes varied from 2 to 5 microM ms-1, depending on SR Ca2+ loading conditions. Following spontaneous activation, the release flux rapidly decayed (tau = 6-12 ms). The rate of termination of release flux was found to be directly related to the magnitude of the flux (r2 = 0.88). 4. The rate of termination of local release flux was slowed in the presence of FK506, a compound that is known to reduce inactivation of SR Ca2+ channels in vitro. 5. These results suggest that termination of release flux during sparks is not due to a spontaneous stochastic decay process or local depletion of Ca2+ from the SR, but rather involves an active extinguishing mechanism such as Ca2+-dependent inactivation or adaptation.
摘要
- 共聚焦钙成像用于测量负载氟-3的离体大鼠心室肌细胞中的自发释放事件（钙火花）。2. 通过采用先前用于描述从细胞平均钙瞬变中宏观钙释放的方法，推导出钙火花背后的微观钙释放通量。3. 局部释放通量的大小在2至5微摩尔/毫秒之间变化，这取决于肌浆网钙负载条件。自发激活后，释放通量迅速衰减（时间常数=6至12毫秒）。发现释放通量的终止速率与通量大小直接相关（r2 = 0.88）。4. 在FK506存在的情况下，局部释放通量的终止速率减慢，FK506是一种已知在体外可减少肌浆网钙通道失活的化合物。5. 这些结果表明，火花期间释放通量的终止不是由于自发随机衰减过程或肌浆网中钙的局部耗尽，而是涉及一种主动熄灭机制，如钙依赖性失活或适应性变化。
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