Regulation of backpropagating action potentials in mitral cell lateral dendrites by A-type potassium currents
Regulation of backpropagating action potentials in mitral cell lateral dendrites by A-type potassium currents
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DOI：
10.1152/jn.00997.2002
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发表时间：
2003-05-01
影响因子：
2.5
通讯作者：
Westbrook, GL
中科院分区：
文献类型：
--
作者：
Christie, JM;Westbrook, GL
分布在二尖瓣细胞外侧树突上的树突突触对嗅球具有强大而广泛的抑制作用。抑制的激活依赖于动作电位对树突的有效穿透。尽管动作电位在顶端树突中的反向传播具有显著的保真度，但对于侧枝状突，这个问题是有争议的。我们使用成对的体细胞和树突记录来测量近端树突节段(SOMA的0-200微米)的动作电位和动作电位产生的钙瞬变来监测远端树突节段的活动(SOMA的200-600微米)。躯体诱发的动作电位在近侧树突减弱。这种衰减不是由于树突的通路阻力受损或基础突触活动所致。然而，单个躯体诱发的动作电位足以在整个侧树突起引起钙瞬变，这表明动作电位到达远端树突间。用4-氨基吡啶(10 MM)阻断A型钾通道(I-A)可阻止直接记录中动作电位的衰减，并显著增加树突状钙瞬变，特别是在远端树突间。我们的结果表明，I-A可能通过控制外侧树突的动作电位幅度来调节嗅球的抑制。
Dendrodendritic synapses, distributed along mitral cell lateral dendrites, provide powerful and extensive inhibition in the olfactory bulb. Activation of inhibition depends on effective penetration of action potentials into dendrites. Although action potentials backpropagate with remarkable fidelity in apical dendrites, this issue is controversial for lateral dendrites. We used paired somatic and dendritic recordings to measure action potentials in proximal dendritic segments (0-200 mum from soma) and action potential-generated calcium transients to monitor activity in distal dendritic segments (200-600 mum from soma). Somatically elicited action potentials were attenuated in proximal lateral dendrites. The attenuation was not due to impaired access resistance in dendrites or to basal synaptic activity. However, a single somatically elicited action potential was sufficient to evoke a calcium transient throughout the lateral dendrite, suggesting that action potentials reach distal dendritic compartments. Block of A-type potassium channels (I-A) with 4-aminopyridine (10 mM) prevented action potential attenuation in direct recordings and significantly increased dendritic calcium transients, particularly in distal dendritic compartments. Our results suggest that I-A may regulate inhibition in the olfactory bulb by controlling action potential amplitudes in lateral dendrites.