Kavalali E T, Zhuo M, Bito H, Tsien R W
Department of Molecular and Cellular Physiology, Beckman Center, Stanford University School of Medicine, California 94305-5426, USA.
Neuron. 1997 Apr;18(4):651-63. doi: 10.1016/s0896-6273(00)80305-0.
Dendritic arbors are critical for the information processing capability of central neurons, but quantitative analysis of their membrane properties has been hampered by their geometrical complexity. Here, we have focused on an important source of Ca2+ entry in dendrites, the voltage-gated Ca2+ channels, by applying the whole-cell voltage-clamp technique to isolated dendritic segments ("dendrosomes") from rat hippocampal neurons. We found that low voltage-activated T-type Ca2+ channels provide a significantly larger fraction of the Ca2+ influx in dendrites than their counterparts in cell bodies. Surprisingly, 60%-70% of the high voltage-activated Ca2+ current in dendrosomes was N and P/Q type, and these channels were susceptible to neurotransmitter inhibition, suggesting a novel physiological role for G protein-regulated Ca2+ channel modulation in controlling dendritic excitability and Ca2+ signaling.
树突分支对于中枢神经元的信息处理能力至关重要，但其膜特性的定量分析一直因其几何复杂性而受到阻碍。在这里，我们通过将全细胞电压钳技术应用于大鼠海马神经元分离的树突段（“树突体”），聚焦于树突中钙离子内流的一个重要来源，即电压门控钙离子通道。我们发现，低电压激活的T型钙离子通道在树突中提供的钙离子内流比例比其在细胞体中的对应通道显著更大。令人惊讶的是，树突体中60%-70%的高电压激活钙离子电流为N型和P/Q型，并且这些通道易受神经递质抑制，这表明G蛋白调节的钙离子通道调制在控制树突兴奋性和钙离子信号传导方面具有新的生理作用。
