Metz Alexia E, Jarsky Tim, Martina Marco, Spruston Nelson
Northwestern University Institute for Neuroscience, Evanston, Illinois 60208, USA.
J Neurosci. 2005 Jun 15;25(24):5763-73. doi: 10.1523/JNEUROSCI.0624-05.2005.
Action potentials in pyramidal neurons are typically followed by an afterdepolarization (ADP), which in many cells contributes to intrinsic burst firing. Despite the ubiquity of this common excitable property, the responsible ion channels have not been identified. Using current-clamp recordings in hippocampal slices, we find that the ADP in CA1 pyramidal neurons is mediated by an Ni2+-sensitive calcium tail current. Voltage-clamp experiments indicate that the Ni2+-sensitive current has a pharmacological and biophysical profile consistent with R-type calcium channels. These channels are available at the resting potential, are activated by the action potential, and remain open long enough to drive the ADP. Because the ADP correlates directly with burst firing in CA1 neurons, R-type calcium channels are crucial to this important cellular behavior, which is known to encode hippocampal place fields and enhance synaptic plasticity.
锥体神经元的动作电位之后通常会出现一个去极化后电位（ADP），在许多细胞中，该电位有助于内在爆发式放电。尽管这种常见的兴奋性特性普遍存在，但尚未确定其相关的离子通道。通过在海马切片中进行电流钳记录，我们发现CA1锥体神经元中的ADP由镍离子（Ni2+）敏感的钙尾电流介导。电压钳实验表明，镍离子敏感电流具有与R型钙通道一致的药理学和生物物理学特征。这些通道在静息电位时可用，由动作电位激活，并保持开放足够长的时间来驱动ADP。由于ADP与CA1神经元中的爆发式放电直接相关，R型钙通道对于这种重要的细胞行为至关重要，已知这种细胞行为可编码海马位置场并增强突触可塑性。
