Functional coupling of ryanodine receptors to KCa channels in smooth muscle cells from rat cerebral arteries.
Functional coupling of ryanodine receptors to KCa channels in smooth muscle cells from rat cerebral arteries.
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Ryanodine受体与大鼠脑动脉平滑肌细胞中的KCA通道的功能偶联。
DOI：
10.1085/jgp.113.2.229
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发表时间：
1999-02
影响因子：
3.8
通讯作者：
Nelson, MT
中科院分区：
文献类型：
--
作者：
Pérez, GJ;Bonev, AD;Patlak, JB;Nelson, MT
在大鼠脑动脉平滑肌细胞中研究了肌浆网中兰尼碱敏感的Ca²⁺释放通道（“Ca²⁺火花”）释放Ca²⁺与KCa通道之间的关系。采用穿孔膜片钳技术、激光二维（x - y）扫描共聚焦显微镜以及荧光Ca²⁺指示剂fluo - 3，同时测量生理膜电位（-40 mV）下的全细胞钾电流和细胞内Ca²⁺。几乎所有（96%）可检测到的Ca²⁺火花都与通过KCa通道激活的自发性瞬时外向电流（STOC）有关。少数火花（128个中的5个）与小于6 pA的电流相关（在 - 40 mV时平均幅度为4.7 pA）。大约41%的STOC发生时没有可检测到的Ca²⁺火花。Ca²⁺火花的幅度与STOC的幅度相关（回归系数为0.8；P < 0.05）。Ca²⁺火花的衰减半衰期（56 ms）比相关的STOC（9 ms）长。与Ca²⁺火花相关的STOC在 - 40 mV时的平均幅度为33 pA。“无火花”的STOC平均幅度较小，为16 pA。Ca²⁺火花期间KCa通道开放概率的极显著增加（>10⁴倍）与火花期间局部Ca²⁺处于1 - 100 μM数量级是一致的。因此，在Ca²⁺火花期间测量到的荧光分数增加（F/Fo）（平均2.04 F/Fo或约310 nM Ca²⁺）似乎明显低估了激活KCa通道的局部Ca²⁺。这些结果表明，大多数引起Ca²⁺火花的兰尼碱受体在功能上与细胞膜表面的KCa通道偶联，为Ca²⁺火花引起STOC这一观点提供了直接支持。
The relationship between Ca2+ release (“Ca2+ sparks”) through ryanodine-sensitive Ca2+ release channels in the sarcoplasmic reticulum and KCa channels was examined in smooth muscle cells from rat cerebral arteries. Whole cell potassium currents at physiological membrane potentials (−40 mV) and intracellular Ca2+ were measured simultaneously, using the perforated patch clamp technique and a laser two-dimensional (x–y) scanning confocal microscope and the fluorescent Ca2+ indicator, fluo-3. Virtually all (96%) detectable Ca2+ sparks were associated with the activation of a spontaneous transient outward current (STOC) through KCa channels. A small number of sparks (5 of 128) were associated with currents smaller than 6 pA (mean amplitude, 4.7 pA, at −40 mV). Approximately 41% of STOCs occurred without a detectable Ca2+ spark. The amplitudes of the Ca2+ sparks correlated with the amplitudes of the STOCs (regression coefficient 0.8; P < 0.05). The half time of decay of Ca2+ sparks (56 ms) was longer than the associated STOCs (9 ms). The mean amplitude of the STOCs, which were associated with Ca2+ sparks, was 33 pA at −40 mV. The mean amplitude of the “sparkless” STOCs was smaller, 16 pA. The very significant increase in KCa channel open probability (>104-fold) during a Ca2+ spark is consistent with local Ca2+ during a spark being in the order of 1–100 μM. Therefore, the increase in fractional fluorescence (F/Fo) measured during a Ca2+ spark (mean 2.04 F/Fo or ∼310 nM Ca2+) appears to significantly underestimate the local Ca2+ that activates KCa channels. These results indicate that the majority of ryanodine receptors that cause Ca2+ sparks are functionally coupled to KCa channels in the surface membrane, providing direct support for the idea that Ca2+ sparks cause STOCs.
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影响因子：
56.9
作者：
NELSON, MT;CHENG, H;LEDERER, WJ
通讯作者：
LEDERER, WJ
影响因子：
3.8
作者：
Horn, R;Marty, A
通讯作者：
Marty, A
DOI：
10.1152/ajpcell.1998.274.6.c1755
发表时间：
1998-06-01
影响因子：
5.5
作者：
Jaggar, JH;Stevenson, AS;Nelson, MT
通讯作者：
Nelson, MT
影响因子：
5.5
作者：
Gordienko, DV;Bolton, TB;Cannell, MB
通讯作者：
Cannell, MB
DOI：
10.1085/jgp.99.6.841
发表时间：
1992-06
期刊：
The Journal of general physiology
影响因子：
--
作者：
Markwardt F;Isenberg G
通讯作者：
Isenberg G