Calcium-induced transitions between the spontaneous miniature outward and the transient outward currents in retinal amacrine cells.
Calcium-induced transitions between the spontaneous miniature outward and the transient outward currents in retinal amacrine cells.
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钙诱导视网膜无长突细胞中自发微型向外电流和瞬时向外电流之间的转变。
DOI：
10.1085/jgp.20028479
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发表时间：
2002-04
影响因子：
3.8
通讯作者：
Slaughter, MM
中科院分区：
文献类型：
--
作者：
Mitra, P;Slaughter, MM
自发性微小外向电流（SMOCs）发生在视网膜无长突细胞的一个子集中，膜电位在−60和−40 mV之间。在更高的去极化电位下，出现瞬时外向电流（Ito），SMOCs消失。SMOC和Ito都是由BK通道携带的K+电流。它们都是通过高电压激活（HVA）Ca2+通道的Ca2+内流产生的，高电压激活（HVA）Ca2+通道刺激咖啡因和ryanodine敏感性商店释放内部Ca2+。Ca2+内流的增加导致SMOC频率的增加，但也导致SMOC平均振幅的下降。这种减少表现出时间依赖性：电压阶跃的后期效果更大。因此，Ca2+流入，虽然需要产生SMOCs，也产生了负调制的幅度。增加Ca2+内流也导致SMOC发生的第一潜伏期下降。这些作用的组合导致SMOCs的消失，沿着出现的Ito在高水平的Ca2+内流。因此，由HVA Ca2+通道的低水平激活引起的低水平Ca2+内流产生在−60至−40 mV范围内随机发生的SMOC。进一步去极化导致HVA Ca 2+通道的更大激活，更大的Ca 2+内流，以及不连续的SMOCs的消失，沿着Ito的出现。基于其特性，视网膜神经元中的SMOCs可能在静止的突触能突触中起突触噪声抑制剂的作用。
Spontaneous miniature outward currents (SMOCs) occur in a subset of retinal amacrine cells at membrane potentials between −60 and −40 mV. At more depolarized potentials, a transient outward current (Ito) appears and SMOCs disappear. Both SMOCs and the Ito are K+ currents carried by BK channels. They both arise from Ca2+ influx through high voltage–activated (HVA) Ca2+ channels, which stimulates release of internal Ca2+ from caffeine- and ryanodine-sensitive stores. An increase in Ca2+ influx resulted in an increase in SMOC frequency, but also led to a decline in SMOC mean amplitude. This reduction showed a temporal dependence: the effect being greater in the latter part of a voltage step. Thus, Ca2+ influx, although required to generate SMOCs, also produced a negative modulation of their amplitudes. Increasing Ca2+ influx also led to a decline in the first latency to SMOC occurrence. A combination of these effects resulted in the disappearance of SMOCs, along with the concomitant appearance of the Ito at high levels of Ca2+ influx. Therefore, low levels of Ca2+ influx, arising from low levels of activation of the HVA Ca2+ channels, produce randomly occurring SMOCs within the range of −60 to −40 mV. Further depolarization leads to greater activation of the HVA Ca2+ channels, larger Ca2+ influx, and the disappearance of discontinuous SMOCs, along with the appearance of the Ito. Based on their characteristics, SMOCs in retinal neurons may function as synaptic noise suppressors at quiescent glutamatergic synapses.
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影响因子：
5.5
作者：
BYERLY, L;CHASE, PB;STIMERS, JR
通讯作者：
STIMERS, JR
影响因子：
5.5
作者：
Carbone, E;Lux, HD;Zucker, H
通讯作者：
Zucker, H
影响因子：
56.9
作者：
GYORKE, S;FILL, M
通讯作者：
FILL, M
影响因子：
5.5
作者：
Hicks, GA;Marrion, NV
通讯作者：
Marrion, NV
DOI：
10.1085/jgp.98.4.751
发表时间：
1991-10
期刊：
The Journal of general physiology
影响因子：
--
作者：
Chow RH
通讯作者：
Chow RH