Spatial distribution of Ca2+ influx in turtle Purkinje cell dendrites in vitro: role of a transient outward current.
Spatial distribution of Ca2+ influx in turtle Purkinje cell dendrites in vitro: role of a transient outward current.
复制标题
体外海龟浦肯野细胞树突中 Ca2 流入的空间分布：瞬时外向电流的作用。
DOI：
10.1152/jn.1993.70.6.2455
复制
发表时间：
1993
影响因子：
2.5
通讯作者：
Ross,WN
中科院分区：
文献类型：
--
作者：
Midtgaard,J;Lasser-Ross,N;Ross,WN
1.在龟小脑的切片制备中，从浦肯野细胞进行细胞内记录。同时，用注射的Fura-2的高速荧光成像检测细胞所有区域中[Ca 2 +]i的变化。通过体内或突触刺激细胞。此外，细胞局部极化与外部电场平行排列的胞体-树突轴。2.索马、光滑树突和棘状树突的[Ca 2 +]i呈电压依赖性变化。躯体区域的变化与Na+峰放电和局部去极化相关。棘状树突中的小[Ca 2 +]i变化与分级电位相关，而较大的变化与Ca 2+动作电位相关。个别Ca 2+尖峰瞬态有时分别发生在不同的树突状区域表现出局部放电。3.棘波相关[Ca 2 +]i瞬变的幅度和空间范围随着体内去极化刺激前膜电位的增加而增加，并因超极化刺激前电位而减少。4-氨基吡啶（4-AP）可显著降低这种依赖性和对Ca 2+峰激活的潜伏期。这些结果表明，一个短暂的A-样电流调节的产生的Ca 2+尖峰和本地化的Ca 2+内流的海龟浦肯野细胞树突。4.电场去极化和胞体内去极化都以类似的方式影响Ca 2+尖峰和[Ca 2 +]i信号的产生。强场刺激可引起棘状树突尖端的局灶性去极化，并在软脑膜表面附近引起局部Ca ~（2+）峰。当这两种刺激都被使用时，它们的效果是相加的。5.攀爬纤维（CF）或平行纤维（PF）刺激与树突状细胞的Ca 2+瞬变的产生。在一些实验中，PF诱导的Ca 2+瞬变仅限于一小部分的多刺树突。这些瞬变的空间分布和幅度的影响体细胞去极化或场刺激的方式类似于他们的效果直接诱发的钙尖峰和一致的参与的短暂外向电流在控制的突触诱导的钙离子内流。6.这些结果表明，内源性钾电导动态调节空间整合和影响区室化的Ca 2+尖峰和[Ca 2 +]i的变化在树突。
1. Intracellular recordings were made from Purkinje cells in a slice preparation of the turtle cerebellum. Simultaneously, changes in [Ca2+]i in all regions of the cell were detected with high-speed fluorescence imaging of injected fura-2. Cells were stimulated either intrasomatically or synaptically. In addition, the cells were polarized locally with an external electrical field aligned parallel to the soma-dendritic axis. 2. The soma, smooth dendrites, and spiny dendrites displayed voltage-dependent changes in [Ca2+]i. Changes in the somatic region were correlated with Na+ spike firing and local depolarization. Small [Ca2+]i changes in the spiny dendrites were correlated with graded potentials and larger changes with Ca2+ action potentials. Individual Ca2+ spike transients sometimes occurred separately in different dendritic regions demonstrating localized firing. 3. The amplitude and spatial extent of spike-related [Ca2+]i transients were increased with intrasomatic depolarizing prestimulus membrane potentials and reduced by hyperpolarizing prestimulus potentials. This dependence and the latency to Ca2+ spike activation were strongly reduced by 4-aminopyridine (4-AP). These results suggest that a transient A-like current regulates the generation of Ca2+ spikes and the localization of Ca2+ influx in turtle Purkinje cell dendrites. 4. Both electric field depolarization and intrasomatic depolarization affected the generation of Ca2+ spikes and [Ca2+]i signals in a similar manner. Strong field stimulation could evoke focal depolarization at the tips of the spiny dendrites and cause local Ca2+ spike generation near the pial surface. When both stimuli were used, their effects were additive. 5. Climbing fiber (CF) or parallel fiber (PF) stimulation were associated with the generation of dendritic Ca2+ transients. In some experiments the PF-induced Ca2+ transients were confined to a small part of the spiny dendrites. The spatial distribution and the amplitude of these transients were influenced by somatic depolarization or field stimulation in a manner similar to their effect on directly evoked Ca2+ spikes and consistent with the involvement of a transient outward current in the control of the synaptically induced Ca2+ influx. 6. These results suggest that the intrinsic potassium conductances dynamically modulate spatial integration and influence the compartmentalization of Ca2+ spikes and [Ca2+]i changes in the dendrites.