Functional Triads Consisting of Ryanodine Receptors, Ca2+ Channels, and Ca2+-Activated K+ Channels in Bullfrog Sympathetic Neurons
Functional Triads Consisting of Ryanodine Receptors, Ca2+ Channels, and Ca2+-Activated K+ Channels in Bullfrog Sympathetic Neurons
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牛蛙交感神经元中由 Ryanodine 受体、Ca2+ 通道和 Ca2+ 激活的 K 通道组成的功能三联体
DOI：
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
K. Kuba
中科院分区：
文献类型：
--
作者：
T. Akita;K. Kuba
荧光ryanodine显示了ryanodine受体在培养的牛蛙交感神经节细胞膜下细胞质（小于几微米）的分布。在含有ryanodine受体的细胞质中，单个或重复动作电位（APs）以恒定的振幅和速率（150 μm/s）以恒定的幅度和速率传播，引起细胞质内Ca2+ ([Ca2+]i)的升高，然后在更深的区域以较慢的减弱方式升高。Ryanodine (10 μM)， Ryanodine受体阻滞剂（和/或半开剂），thapsigargin (1 - 2 μM)， Ca2+泵阻滞剂，ω-conotoxin GVIA (ω-CgTx, 1 μM)， n型Ca2+通道阻滞剂，阻断了快速传播，但不影响较慢的传播。因此，Ca2+进入触发了Ca2+诱导的Ca2+释放（CICR）在膜下区域的再生激活，随后缓冲Ca2+扩散到更深的细胞质。计算机模拟假设Ca2+释放在膜下区域再现Ca2+动力学。Ryanodine或thapsigargin将AP的尖峰复极率降低到80%，但在iberiotoxin （IbTx, 100 nM）、一种bk型Ca2+激活的K+通道阻滞剂或ω-CgTx的存在下，这两种物质都将AP的尖峰复极率降低到50%。在50 Hz的频率下，脉冲复极率和单个ap诱导的[Ca2+]i的上升幅度逐渐下降到一个平台，但在ryanodine或thapsigarin的存在下下降较少。每个[Ca2+]i的上升幅度与脉冲复极化中ibtx敏感成分的减少密切相关。apamine -sensitive sk -型Ca2+激活的K+电流，在APs后超极化的基础上，在重复APs期间增加，衰减速度快于伴随的[Ca2+]i的上升，并被CICR阻滞剂抑制。因此，在牛蛙交感神经元中，ryanodine受体与n型Ca2+通道和BK通道形成功能性三联体，并与SK通道松散偶联，可塑性地调节AP。
Fluorescent ryanodine revealed the distribution of ryanodine receptors in the submembrane cytoplasm (less than a few micrometers) of cultured bullfrog sympathetic ganglion cells. Rises in cytosolic Ca2+ ([Ca2+]i) elicited by single or repetitive action potentials (APs) propagated at a high speed (150 μm/s) in constant amplitude and rate of rise in the cytoplasm bearing ryanodine receptors, and then in the slower, waning manner in the deeper region. Ryanodine (10 μM), a ryanodine receptor blocker (and/or a half opener), or thapsigargin (1–2 μM), a Ca2+-pump blocker, or ω-conotoxin GVIA (ω-CgTx, 1 μM), a N-type Ca2+ channel blocker, blocked the fast propagation, but did not affect the slower spread. Ca2+ entry thus triggered the regenerative activation of Ca2+-induced Ca2+ release (CICR) in the submembrane region, followed by buffered Ca2+ diffusion in the deeper cytoplasm. Computer simulation assuming Ca2+ release in the submembrane region reproduced the Ca2+ dynamics. Ryanodine or thapsigargin decreased the rate of spike repolarization of an AP to 80%, but not in the presence of iberiotoxin (IbTx, 100 nM), a BK-type Ca2+-activated K+ channel blocker, or ω-CgTx, both of which decreased the rate to 50%. The spike repolarization rate and the amplitude of a single AP-induced rise in [Ca2+]i gradually decreased to a plateau during repetition of APs at 50 Hz, but reduced less in the presence of ryanodine or thapsigargin. The amplitude of each of the [Ca2+]i rise correlated well with the reduction in the IbTx-sensitive component of spike repolarization. The apamin-sensitive SK-type Ca2+-activated K+ current, underlying the afterhyperpolarization of APs, increased during repetitive APs, decayed faster than the accompanying rise in [Ca2+]i, and was suppressed by CICR blockers. Thus, ryanodine receptors form a functional triad with N-type Ca2+ channels and BK channels, and a loose coupling with SK channels in bullfrog sympathetic neurons, plastically modulating AP.
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影响因子：
2.5
作者：
L. A. Merriam;F. Scornik;R. Parsons
通讯作者：
L. A. Merriam;F. Scornik;R. Parsons
影响因子：
2.5
作者：
K. Moore;A. Cohen;J. Kao;D. Weinreich
通讯作者：
K. Moore;A. Cohen;J. Kao;D. Weinreich
影响因子：
3.4
作者：
Smith, GD
通讯作者：
Smith, GD
影响因子：
56.9
作者：
LLINAS, R;SUGIMORI, M;SILVER, RB
通讯作者：
SILVER, RB
影响因子：
56.9
作者：
ALLBRITTON, NL;MEYER, T;STRYER, L
通讯作者：
STRYER, L