Action potential-evoked and ryanodine-sensitive spontaneous Ca2+ transients at the presynaptic terminal of a developing CNS inhibitory synapse
Action potential-evoked and ryanodine-sensitive spontaneous Ca2+ transients at the presynaptic terminal of a developing CNS inhibitory synapse
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DOI：
10.1523/jneurosci.1397-04.2004
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发表时间：
2004-08-04
影响因子：
5.3
通讯作者：
Llano, I
中科院分区：
文献类型：
--
作者：
Conti, R;Tan, YP;Llano, I
据报道，在小脑篮状中间神经元的假定轴突末端中存在依赖于细胞内钙池激活的自发钙瞬变（SCaT）。我们使用双光子成像技术光学识别幼鼠（11-16 日龄）急性小脑切片中的篮子末端，并研究明确定位于这些区域的 SCaT 的特性。全细胞记录配置和预加载技术交替用于在中间神经元中加载钙依赖性染料，并将 SCaT 与动作电位诱发的钙瞬变进行比较。在篮子末端观察到 SCaT 的频率在使用 10 muM ryanodine 浴后显着增加，并且不依赖于 P/Q 或 N 型电压依赖性钙通道激活。它们起源于特定地点，在这些地点可以产生时间间隔小至 200 毫秒的事件爆发。它们的起源位点平均间隔 6 微米，并且优先位于轴突末端附近。 SCaT 的振幅与单一动作电位引起的 Ca2+ 升高相当，导致神经递质释放，这一点通过突触后浦肯野细胞中预加载终端和诱发 IPSC 的并行记录证实。这些结果支持这样的假设：篮末端的 SCaT 是浦肯野细胞的大型微型 IPSC 特征的基础。
The existence of spontaneous calcium transients (SCaTs) dependent on intracellular store activation has been reported in putative axonal terminals of cerebellar basket interneurons. We used the two-photon imaging technique to optically identify basket terminals in acute cerebellar slices of young rats (11-16 d old) and study the properties of SCaTs unambiguously localized in these regions. The whole-cell recording configuration and preloading technique were alternatively used to load the calcium-dependent dye in the interneuron and compare SCaTs with action potential evoked calcium transients. SCaTs were observed in the basket terminals at frequencies that were significantly increased after bath application of 10 muM ryanodine and did not depend on P/Q- or N-type voltage-dependent calcium channel activation. They originated at specific sites where bursts of events with temporal separation as small as 200 msec could be generated. Their sites of origin were spaced on average 6 mum apart and were preferentially located near axonal endings. SCaTs had amplitudes comparable with those of Ca2+ rises evoked by single action potentials that lead to release of neurotransmitter, as confirmed by parallel recordings of preloaded terminals and evoked IPSCs in the postsynaptic Purkinje cells. These results support the hypothesis that SCaTs at basket terminals underlie the large miniature IPSCs characteristic of Purkinje cells.