Characterization of Voltage-Gated Ca2+ Conductances in Layer 5 Neocortical Pyramidal Neurons from Rats
Characterization of Voltage-Gated Ca2+ Conductances in Layer 5 Neocortical Pyramidal Neurons from Rats
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DOI：
10.1371/journal.pone.0004841
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发表时间：
2009-04-01
期刊：
影响因子：
3.7
通讯作者：
Korngreen, Alon
中科院分区：
文献类型：
--
作者：
Almog, Mara;Korngreen, Alon
神经元电压门控Ca2+通道参与电信号和将这些信号转化为细胞质钙变化。电压门控Ca2+通道的一个重要功能是产生再生树突Ca2+尖峰。然而，用于产生这些尖峰的Ca2+依赖机制仅部分被理解。为了开始研究这一机制，我们开始使用膜片钳技术的有核配置，从动力学和药理学上鉴定大鼠体感觉皮层第5层锥体神经元中体细胞电压门控Ca2+通道的亚型。总Ba2+电流的激活动力学显示电导激活仅在中高压下发生，表明t型钙通道不存在于斑块中。稳态失活方案结合药理学揭示了r型通道的表达。此外，药理学实验确定了5种电压门控Ca2+通道亚型- l -， N-， R-和P/ q型。最后，使用生理衍生的电压钳方案，包括钙峰值方案和模拟反向传播动作电位（mBPAP）方案，检查Ca2+电导的激活。这些实验使我们能够提出在生理条件下激活Ca2+电流时，五种Ca2+通道亚型对Ca2+电流的可能贡献。
Neuronal voltage-gated Ca2+ channels are involved in electrical signalling and in converting these signals into cytoplasmic calcium changes. One important function of voltage-gated Ca2+ channels is generating regenerative dendritic Ca2+ spikes. However, the Ca2+ dependent mechanisms used to create these spikes are only partially understood. To start investigating this mechanism, we set out to kinetically and pharmacologically identify the sub-types of somatic voltage-gated Ca2+ channels in pyramidal neurons from layer 5 of rat somatosensory cortex, using the nucleated configuration of the patch-clamp technique. The activation kinetics of the total Ba2+ current revealed conductance activation only at medium and high voltages suggesting that T-type calcium channels were not present in the patches. Steady-state inactivation protocols in combination with pharmacology revealed the expression of R-type channels. Furthermore, pharmacological experiments identified 5 voltage-gated Ca2+ channel sub-types -L-, N-, R- and P/Q-type. Finally, the activation of the Ca2+ conductances was examined using physiologically derived voltage-clamp protocols including a calcium spike protocol and a mock back-propagating action potential (mBPAP) protocol. These experiments enable us to suggest the possible contribution of the five Ca2+ channel sub-types to Ca2+ current flow during activation under physiological conditions.