Dihydropyridine-sensitive, voltage-gated Ca2+ channels contribute to the resting intracellular Ca2+ concentration of hippocampal CA1 pyramidal neurons.
Dihydropyridine-sensitive, voltage-gated Ca2+ channels contribute to the resting intracellular Ca2+ concentration of hippocampal CA1 pyramidal neurons.
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二氢吡啶敏感的电压门控 Ca2 通道有助于海马 CA1 锥体神经元的静息细胞内 Ca2 浓度。
DOI：
10.1152/jn.1996.76.5.3460
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Johnston,D
中科院分区：
文献类型：
--
作者：
Magee,JC;Avery,RB;Christie,BR;Johnston,D
1.采用全细胞记录和高速荧光成像技术，研究电压门控性钙通道对海马CA 1区锥体神经元静息态钙浓度（[Ca 2 +]i）的影响。2.长时间的膜超极化产生，在电压依赖性的方式，持续减少[Ca 2 +]i的体细胞和顶端树突状区域的神经元。这种超极化诱导的[Ca 2 +]i降低发生的时间常数约为1 s，并保持只要膜电位保持在新的水平。比率测量表明，与-80 mV相比，在-50 mV的保持电位下[Ca 2 +]i显著升高。3. 200 μ M Cd ~（2+）和10 μ M尼莫地平可显著降低超极化引起的[Ca ~（2+）]i降低，而50 μ M Ni ~（2+）仅轻微抑制。在近端顶树突中观察到[Ca 2 +]i的最大幅度降低，Ca 2+变化的幅度随着离索马的距离的增加而降低。4.从急性分离的海马锥体神经元的全细胞记录揭示了缓慢失活的Ca 2+电流，其具有与超极化诱导的[Ca 2 +]i降低相似的电压依赖性和药理学。5.这些数据表明，一群二氢吡啶敏感的Ca 2+通道在静息膜电位下是活跃的，并且这种通道激活显著有助于静息[Ca 2 +]i。这些通道似乎存在于整个神经元中，并且可能最密集地位于近端顶端树突中。
1. Whole cell recordings and high-speed fluorescence imaging were used to investigate the contribution of voltage-gated Ca2+ channels to the resting Ca2+ concentration ([Ca2+]i) in hippocampal CA1 pyramidal neurons. 2. Prolonged membrane hyperpolarization produced, in a voltage-dependent manner, sustained decreases in [Ca2+]i in the somatic and apical dendritic regions of the neuron. This hyperpolarization-induced decrease in [Ca2+]i occurred with a time constant of approximately 1 s and was maintained for as long as the membrane potential was held at the new level. Ratiometric measures showed that [Ca2+]i is significantly elevated at holding potentials of -50 mV compared with -80 mV. 3. The hyperpolarization-induced decrease in [Ca2+]i was reduced significantly by 200 microM Cd2+ and 10 microM nimodipine, but was only slightly inhibited by 50 microM Ni2+. The largest amplitude decrease in [Ca2+]i was observed in the proximal apical dendrites with the amplitude of the Ca2+ change decreasing with further distance from the soma. 4. Whole cell recordings from acutely isolated hippocampal pyramidal neurons reveal a slowly inactivating Ca2+ current with similar voltage dependence and pharmacology to the hyperpolarization-induced decrease in [Ca2+]i. 5. The data suggest that a population of dihydropyridine-sensitive Ca2+ channels are active at resting membrane potentials and that this channel activation significantly contributes to the resting [Ca2+]i. These channels appear to be present throughout the neuron and may be located most densely in the proximal apical dendrites.