Iberiotoxin-sensitive large conductance Ca2+-dependent K+ (BK) channels regulate the spike configuration in the burst firing of cerebellar Purkinje neurons
- 作者：Hashem Haghdoost-Yazdi ; Mahyar Janahmadi ; Gila Behzadi
- 关键词：Cerebellar Purkinje cell ; BK channel ; Iberiotoxin ; 4-AP-induced burst ; Spike configuration
- 刊名：Brain Research
- 出版年：2008
- 期刊代码：8_00068993
- 类别：neu
- 出版时间：30 May 2008
- 卷：1212
- 期：Complete
- 页码：1-8
- 文件大小：624 K
摘要
Cerebellar Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex. Mature PCs discharge either tonically Na+ spikes or bursts of Na+ spikes ending to a Ca2+ spike. These cells express inactivating and non-inactivating large conductance Ca2+-dependent K+ (BK) channels in their soma and dendrites. Somatic intracellular recording of acutely prepared brain slices was performed to examine the role of BK channels-mediated current in the tonic and burst firing of PCs. Continuous injection of a negative DC current was used to both suppress the spontaneous activity and stabilize the resting membrane potential around − 70 mV. Then, the short depolarizing current injection was used to evoke spike discharge. For establishing of the burst firing, 4-aminopyridine (4-AP) was bath applied to the bath solution. Blockade of BK channels with iberiotoxin (IbTx); a specific blocker of BK channels, did not affect the Na+ spike configuration in the tonic firing but caused a remarkable change in the shape of Na+ and Ca2+ spikes in 4-AP-induced burst. Our results showed that during the burst firing, strong activation of IbTx-sensitive BK channels enhances the amplitude of fast afterhyperpolarization while decreases the duration of both Na+ and Ca2+ spikes. The current from these channels contributes to both the repolarizing of Na+ spike in the burst and setting of the amplitude of post-pulse AHP that occurs immediately after a depolarizing pulse. These data reveal an important role of IbTx-sensitive BK current in regulating of the spike configuration during the burst firing of PCs.