Calcium sparks in the intact gerbil spiral modiolar artery.
Calcium sparks in the intact gerbil spiral modiolar artery.
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DOI：
10.1186/1472-6793-11-15
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发表时间：
2011-08-26
期刊：
影响因子：
--
通讯作者：
Wangemann P
中科院分区：
文献类型：
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作者：
Krishnamoorthy G;Regehr K;Berge S;Scherer EQ;Wangemann P
钙火花是兰尼定受体介导的瞬时钙信号，通过激活血管平滑肌细胞的大电导钙激活钾(BK)通道，使膜电位超极化。与电压依赖的钙通道一起，它们形成一个信号单位，对血管直径和肌源性张力的调节产生血管扩张的影响。到目前为止，在螺旋动脉中钙火花的存在和作用还没有被探索过，螺旋动脉是控制流向耳蜗的血液的末端动脉。本研究的目的是确定在完整的沙土鼠螺旋动脉中钙火花的存在和性质。从负载了Fluo-4 AM的完整动脉的平滑肌细胞记录到钙火花钙火花产生的频率为2.6赫兹，上升时间为17ms，半衰期为20ms。兰诺定在3分钟内使放电频率从2.6赫兹降至0.6赫兹。咖啡因(1 MM)使放电频率从2.3赫兹增加到3.3赫兹，上升和半衰期分别从17到19毫秒和20到23毫秒延长。钾的升高(3.6到37.5毫米)，可能是通过去极化，使火花频率从2.4赫兹增加到3.2赫兹。兰诺定和去极化都不会改变上升或下降时间。这是第一次表征螺旋动脉的平滑肌细胞中的钙火花。提示钙火花对耳蜗螺旋动脉管径和耳蜗血流量有调节作用。
Calcium sparks are ryanodine receptor mediated transient calcium signals that have been shown to hyperpolarize the membrane potential by activating large conductance calcium activated potassium (BK) channels in vascular smooth muscle cells. Along with voltage-dependent calcium channels, they form a signaling unit that has a vasodilatory influence on vascular diameter and regulation of myogenic tone. The existence and role of calcium sparks has hitherto been unexplored in the spiral modiolar artery, the end artery that controls blood flow to the cochlea. The goal of the present study was to determine the presence and properties of calcium sparks in the intact gerbil spiral modiolar artery. Calcium sparks were recorded from smooth muscle cells of intact arteries loaded with fluo-4 AM. Calcium sparks occurred with a frequency of 2.6 Hz, a rise time of 17 ms and a time to half-decay of 20 ms. Ryanodine reduced spark frequency within 3 min from 2.6 to 0.6 Hz. Caffeine (1 mM) increased spark frequency from 2.3 to 3.3 Hz and prolonged rise and half-decay times from 17 to 19 ms and from 20 to 23 ms, respectively. Elevation of potassium (3.6 to 37.5 mM), presumably via depolarization, increased spark frequency from 2.4 to 3.2 Hz. Neither ryanodine nor depolarization changed rise or decay times. This is the first characterization of calcium sparks in smooth muscle cells of the spiral modiolar artery. The results suggest that calcium sparks may regulate the diameter of the spiral modiolar artery and cochlear blood flow.