Contribution of cyclic-nucleotide-gated channels to the resting conductance of olfactory receptor neurons.
Contribution of cyclic-nucleotide-gated channels to the resting conductance of olfactory receptor neurons.
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环核苷酸门控通道对嗅觉受体神经元静息电导的贡献。
DOI：
10.1016/s0006-3495(03)70064-2
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Kleene,StevenJ
中科院分区：
文献类型：
--
作者：
Pun,RaymundYK;Kleene,StevenJ
用全细胞和穿孔斑记录法研究了未受刺激的蛙嗅感受器神经元的基础电导。输入电导在− 80 mV和− 60 mV之间测量，在生理盐水中平均为0.25 nS。进行研究以确定输入电导的一部分是否是由于神经元环核苷酸门控（CNG）通道的门控。为了支持这一观点，神经元静息电导减少了五种治疗，减少通过CNG通道的电流：外部应用二价阳离子或阿米洛利;治疗与任何两个腺苷酸环化酶抑制剂;和应用AMP-PNP，腺苷酸环化酶的竞争性底物。二价阳离子或环化酶抑制剂阻断的电流在0 mV附近逆转，如CNG电流所预期。在生理条件下，CNG通道的门控对静息神经元电导的贡献为0.06nS。这意味着静息cAMP浓度为0.1-0.3μM。一个理论模型表明，含有0.1-0.3μM cAMP的神经元准备对非常小的嗅觉刺激做出最大可能的去极化反应。尽管CNG通道在静止时打开降低了由给定受体电流引起的电压变化，但它更显著地增加了由[cAMP]的给定增加引起的受体电流。
The basal conductance of unstimulated frog olfactory receptor neurons was investigated using whole-cell and perforated-patch recording. The input conductance, measured between −80mV and −60mV, averaged 0.25nS in physiological saline. Studies were conducted to determine whether part of the input conductance is due to gating of neuronal cyclic-nucleotide-gated (CNG) channels. In support of this idea, the neuronal resting conductance was reduced by each of five treatments that reduce current through CNG channels: external application of divalent cations or amiloride; treatment with either of two adenylate cyclase inhibitors; and application of AMP-PNP, a competitive substrate for adenylate cyclase. The current blocked by divalent cations or by a cyclase inhibitor reversed near 0mV, as expected for a CNG current. Under physiological conditions, gating of CNG channels contributes ∼0.06nS to the resting neuronal conductance. This implies a resting cAMP concentration of 0.1–0.3μM. A theoretical model suggests that a neuron containing 0.1–0.3μM cAMP is poised to give the largest possible depolarization in response to a very small olfactory stimulus. Although having CNG channels open at rest decreases the voltage change resulting from a given receptor current, it more substantially increases the receptor current resulting from a given increase in [cAMP].