Modulation by K+ channels of action potential‐evoked intracellular Ca2+ concentration rises in rat cerebellar basket cell axons
Modulation by K+ channels of action potential‐evoked intracellular Ca2+ concentration rises in rat cerebellar basket cell axons
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K+ 通道对动作电位的调节引起大鼠小脑篮细胞轴突细胞内 Ca2+ 浓度升高
DOI：
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Isabel Llano
中科院分区：
文献类型：
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作者：
Y. P. Tan;Isabel Llano
采用双光子激光扫描显微镜和全细胞记录技术研究了大鼠小脑篮细胞轴突动作电位诱发[Ca2+]i升高，以确定控制轴突动作电位形状的K+通道。2利用浦肯野细胞IPSCs的全细胞记录来筛选可能导致轴突复极化的K+通道亚型。α‐树突毒素、4‐氨基吡啶、白藜芦醇毒素和四乙基氯化铵增加了IPSC的速率和/或幅度，而iberiotoxin和apamin对IPSC没有影响。这些K+通道阻滞剂对篮细胞轴突由动作电位引起的[Ca2+]i升高的影响可分为三组：4 -氨基吡啶强烈增加动作电位诱发的[Ca2+]i；四乙基铵和肉毒杆菌毒素单独作用无效，但增强了4 -氨基吡啶的作用；α‐树突毒素没有作用。我们得出结论，小脑篮细胞包含至少三个药理学上不同的K+通道，它们通过不同的机制调节递质释放。4‐氨基吡啶敏感，α‐树突毒素不敏感的K+通道主要负责篮状细胞突触前末端的复极化。被肉毒杆菌毒素和四乙基铵阻断的K+通道在复极化中起次要作用。α‐树突毒素敏感通道不参与轴突动作电位波形的形成。因此，最后两种通道必须通过与轴突动作电位拓宽无关的途径来控制突触活动。
1 Action potential‐evoked [Ca2+]i rises in basket cell axons of rat cerebellar slices were studied using two‐photon laser scanning microscopy and whole‐cell recording, to identify the K+ channels controlling the shape of the axonal action potential. 2 Whole‐cell recordings of Purkinje cell IPSCs were used to screen K+ channel subtypes which could contribute to axonal repolarization. α‐Dendrotoxin, 4‐aminopyridine, charybdotoxin and tetraethylammonium chloride increased IPSC rate and/or amplitude, whereas iberiotoxin and apamin failed to affect the IPSCs. 3 The effects of those K+ channel blockers that enhanced transmitter release on the [Ca2+]i rises elicited in basket cell axons by action potentials fell into three groups: 4‐aminopyridine strongly increased action potential‐evoked [Ca2+]i; tetraethylammonium and charybdotoxin were ineffective alone but augmented the effects of 4‐aminopyridine; α‐dendrotoxin had no effect. 4 We conclude that cerebellar basket cells contain at least three pharmacologically distinct K+ channels, which regulate transmitter release through different mechanisms. 4‐Aminopyridine‐sensitive, α‐dendrotoxin‐insensitive K+ channels are mainly responsible for repolarization in basket cell presynaptic terminals. K+ channels blocked by charybdotoxin and tetraethylammonium have a minor role in repolarization. α‐Dendrotoxin‐sensitive channels are not involved in shaping the axonal action potential waveform. The two last types of channels must therefore exert control of synaptic activity through a pathway unrelated to axonal action potential broadening.
DOI：
10.1073/pnas.88.2.380
发表时间：
1991-01-01
影响因子：
11.1
作者：
JACKSON, MB;KONNERTH, A;AUGUSTINE, GJ
通讯作者：
AUGUSTINE, GJ