Voltage-gated calcium currents in isolated retinal ganglion cells of the cat.
Voltage-gated calcium currents in isolated retinal ganglion cells of the cat.
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猫离体视网膜神经节细胞中的电压门控钙电流。
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
A. Kaneko
中科院分区：
文献类型：
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作者：
M. Kaneda;A. Kaneko
在电压钳条件下，用膜片管全细胞构型记录成年猫视网膜神经节细胞电压门控性钙电流(ICA)。用离子替代和选择性阻断剂从电压依赖性钾、钠电流中分离出ICa。ICa是通过去极化细胞从-97 mV的保持电位(VH)到比-57 mV更正的电压激活的。所有记录的细胞都表现出类似的ICA激活的电压依赖性：约-23 mV时激活50%。ICA的电流-电压(I-V)关系呈对称的钟形，在-7 mV附近有一个单峰。VH为-57 mV和VH为-97 mV时记录的I-V曲线基本相同。在去极化指令中，ICA的幅度逐渐降低。ICA的失活依赖于细胞内钙的内流。当细胞外钙被BA取代时，ICA变得更持久，或者当细胞内负载30 mM EGTA时，ICA变得更持久。硝苯地平(10(-4)M)可逆地抑制ICA。BAY K 8644的作用呈双峰型：低浓度(10(-8)M)增强，高浓度(10(-4)M)抑制。所有这些特征都与前人对高门槛(L型)颈内动脉的研究结果一致。成年猫视网膜神经节细胞记录的ICA类型与新生大鼠不同。
Voltage-gated calcium current (ICa) was recorded from retinal ganglion cells dissociated from the adult cat under the voltage-clamp condition using a patch pipette in the whole cell configuration. ICa was isolated from the voltage-dependent potassium and sodium currents by ion substitution and selective blockers. ICa was activated by depolarization of the cell from a holding potential (Vh) of -97 mV to more positive voltages than -57 mV. All recorded cells showed similar voltage dependence of ICa activation: 50% activation at about -23 mV. Current-voltage (I-V) relationship of ICa showed a symmetrical bell-shape with a single peak at around -7 mV. The I-V curve recorded with Vh of -57 mV was nearly identical to that obtained with Vh of -97 mV. During a depolarizing command, the amplitude of ICa gradually decreased. Inactivation of ICa depended on Ca influx into the cell. ICa became more sustained either when the extracellular Ca was replaced by Ba, or when the cell was loaded with 30 mM EGTA. Nifedipine (10(-4) M) inhibited ICa reversibly. Effects of Bay K 8644 were bimodal: augmentation at a low concentration (10(-8) M) and suppression at a high concentration (10(-4) M). All these characteristics are identical to the previous findings for the high-threshold (L-type) ICa. The type of ICa recorded from the retinal ganglion cells in the adult cat is different from those in newborn rats.