Spatial distribution and characteristics of voltage-gated calcium signals within visual interneurons
Spatial distribution and characteristics of voltage-gated calcium signals within visual interneurons
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DOI：
10.1152/jn.2000.83.2.1039
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发表时间：
2000-02-01
影响因子：
2.5
通讯作者：
Borst, A
中科院分区：
文献类型：
--
作者：
Haag, J;Borst, A
视觉中间神经元内电压门控钙信号的空间分布和特征。神经生理学杂志。83：1039 - 1051，2000.目前对昆虫钙电流的认识大多来自于对培养或游离胞体的研究。到目前为止，只有很少的数据可用于：神经元，包括其树突和突触前结构的钙电流。在这里，我们结合了开关电极电压钳技术与光学记录使用钙敏感染料在确定的苍蝇视觉中间神经元在体内的电压依赖性和动态的钙电流定量和空间分辨的方式来表征。对于所考虑的所有三种细胞类型，即，在离心水平（CH）、水平系统（HS）和垂直系统（VS）细胞中，激活曲线相当平坦，并且在细胞的树突以及突触前区域中覆盖-60至-20 mV的电压范围。在HS和VS细胞中，时间常数达到400 - 700 ms。在细胞的不同区域中测定的钙动力学是相似的，除了HS和VS细胞中轴突和树突之间的一小段，其中钙增加明显更快。总之，结果表明，存在一个低电压激活的钙电流，很少或没有失活的树突状细胞以及突触前区域的苍蝇小叶板切向细胞。
Spatial distribution and characteristics of voltage-gated calcium signals within visual interneurons. J. Neurophysiol. 83: 1039-1051, 2000. Most of our knowledge about insect calcium currents is derived from studies on cultured or dissociated somata. So far, only little data on calcium currents are available for: neurons including their dendritic and presynaptic structures. Here we combined the switched-electrode voltage-clamp technique with optical recording using calcium-sensitive dyes in identified fly visual interneurons in vivo to characterize the voltage dependence and dynamics of calcium currents quantitatively and in a spatially resolved way. For all three cell types considered, i.e., centrifugal horizontal (CH), horizontal system (HS), and vertical system (VS) cells, the activation curve is rather flat and covers a voltage range from -60 to -20 mV in dendritic as well as presynaptic areas of the cells. The calcium increase is fastest for CH cells with a time constant of similar to 70 ms. In HS and VS cells, the time constant amounts to 400-700 ms. The calcium dynamics as determined in different regions of the cells are similar except for a small segment between the axon and the dendrite in HS and VS cells, where the calcium increase is significantly faster. In summary, the results show the existence of a low-voltage-activated calcium current with little or no inactivation in dendritic as well as presynaptic regions of fly lobula plate tangential cells.