'Pressure-flow'-triggered intracellular Ca2+ transients in rat cardiac myocytes:: possible mechanisms and role of mitochondria
'Pressure-flow'-triggered intracellular Ca2+ transients in rat cardiac myocytes:: possible mechanisms and role of mitochondria
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DOI：
10.1113/jphysiol.2007.149294
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发表时间：
2008-03-01
影响因子：
5.5
通讯作者：
Morad, Martin
中科院分区：
文献类型：
--
作者：
Belmonte, Stephen;Morad, Martin
完整心脏中的心肌细胞在每个心动周期期间暴露于剪切力/流体力。在这里，我们描述了一种新的Ca 2+信号通路，产生的“加压流”（PF）的解决方案，导致激活缓慢发展（类似于300毫秒）Ca 2+瞬变持续类似于1700毫秒在室温下。虽然随后的PF（应用约10-30秒后）产生小得多或检测不到的反应，这种瞬变可以重新激活后咖啡因或氯化钾诱导的Ca 2+释放，这表明一个小的，但易分解的，Ca 2+池作为其激活的来源。PF触发的Ca 2+瞬变可以在无Ca 2+溶液中激活，或者在分别使用Cd 2+、Gd 3+或Ni 2+阻断电压门控Ca 2+通道、牵张激活通道（SAC）或Na+-Ca 2+交换器（NCX）的溶液中激活。PF触发的Ca 2+瞬变显着小于静态比电起搏的心肌细胞。起搏的Ca 2+瞬变激活的PF触发的Ca 2+瞬变的峰值并不显着小于正常情况下产生的，这表明功能独立的Ca 2+池起搏和PF触发的瞬变。一氧化氮（NO）或IP 3信号通路的抑制并没有改变PF触发的Ca 2+瞬变。另一方面，线粒体代谢解偶联剂FCCP，在寡霉素（以防止ATP耗竭）的存在下，可逆地抑制PF触发的Ca 2+瞬变，线粒体Ca 2+单向转运体（mCU）阻滞剂Ru 360也是如此。还原剂DTT和活性氧（ROS）清除剂tempol，以及线粒体NCX（mNCX）阻断剂CGP-37157，抑制PF触发的Ca 2+瞬变。在rhod-2 AM负载和透化的细胞，线粒体Ca 2+的共聚焦成像显示了短暂的增加，Ca 2+的咖啡因曝光和减少线粒体Ca 2+的PF脉冲的应用程序的解决方案。这些信号被无Na+或含CGP-37157的溶液强烈抑制，暗示mNCX介导Ca 2+释放过程。我们的结论是，大鼠心肌细胞加压流脉冲的解决方案触发释放的钙离子从一个商店，似乎访问线粒体Ca 2+。
Cardiac myocytes, in the intact heart, are exposed to shear/fluid forces during each cardiac cycle. Here we describe a novel Ca2+ signalling pathway, generated by 'pressurized flows' (PFs) of solutions, resulting in the activation of slowly developing (similar to 300 ms) Ca2+ transients lasting similar to 1700 ms at room temperature. Though subsequent PFs (applied some 10-30 s later) produced much smaller or undetectable responses, such transients could be reactivated following caffeine- or KCl-induced Ca2+ releases, suggesting that a small, but replenishable, Ca2+ pool serves as the source for their activation. PF-triggered Ca2+ transients could be activated in Ca2+-free solutions or in solutions that block voltage-gated Ca2+ channels, stretch-activated channels (SACs), or the Na+-Ca2+ exchanger (NCX), using Cd2+, Gd3+, or Ni2+, respectively. PF-triggered Ca2+ transients were significantly smaller in quiescent than in electrically paced myocytes. Paced Ca2+ transients activated at the peak of PF-triggered Ca2+ transients were not significantly smaller than those produced normally, suggesting functionally separate Ca2+ pools for paced and PF-triggered transients. Suppression of nitric oxide (NO) or IP3 signalling pathways did not alter the PF-triggered Ca2+ transients. On the other hand, mitochondrial metabolic uncoupler FCCP, in the presence of oligomycin (to prevent ATP depletion), reversibly suppressed PF-triggered Ca2+ transients, as did the mitochondrial Ca2+ uniporter (mCU) blocker, Ru360. Reducing agent DTT and reactive oxygen species (ROS) scavenger tempol, as well as mitochondrial NCX (mNCX) blocker CGP-37157, inhibited PF-triggered Ca2+ transients. In rhod-2 AM-loaded and permeabilized cells, confocal imaging of mitochondrial Ca2+ showed a transient increase in Ca2+ on caffeine exposure and a decrease in mitochondrial Ca2+ on application of PF pulses of solution. These signals were strongly suppressed by either Na+-free or CGP-37157-containing solutions, implicating mNCX in mediating the Ca2+ release process. We conclude that subjecting rat cardiac myocytes to pressurized flow pulses of solutions triggers the release of Ca2+ from a store that appears to access mitochondrial Ca2+.