NONLINEAR AMPLIFICATION BY CALCIUM-DEPENDENT CHLORIDE CHANNELS IN OLFACTORY RECEPTOR-CELLS
NONLINEAR AMPLIFICATION BY CALCIUM-DEPENDENT CHLORIDE CHANNELS IN OLFACTORY RECEPTOR-CELLS
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DOI：
10.1038/366283a0
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发表时间：
1993-11-18
期刊：
影响因子：
64.8
通讯作者：
GOLD, GH
中科院分区：
文献类型：
--
作者：
LOWE, G;GOLD, GH
嗅觉在哺乳动物中高度进化，能够区分大量的气味，检测阈值低至10（-17）M（参考文献1）。尽管生物化学和分子生物学研究已经揭示了哺乳动物嗅觉传导的几个特征2 -11，但气味诱导的膜电流仍然难以捉摸。在两栖动物中，该电流由环核苷酸门控通道12 -15介导，其通过Na+和Ca+流入16，17以及随后通过Ca 2+依赖性Cl-通道18，19的Cl-流出来使细胞去极化。然而，Cl-电流在哺乳动物中可能不存在，因为它的作用与两栖动物的水生栖息地有关18。在这里，我们表明，在大鼠嗅觉受体细胞的转导电流是由环核苷酸门控通道。Cl-电流也存在，并赋予转导电流与陡峭的sigmoidal依赖于环AMP浓度在大鼠和两栖动物，表明一个新的功能的Cl-通道：非线性放大的转导信号，从而阈上响应相对于基础转导噪声增强。
THE sense of smell is highly evolved in mammals, allowing discrimination between a vast number of odorants, with detection thresholds as low as 10(-17) M (ref. 1). Although several features of mammalian olfactory transduction have been revealed by biochemical and molecular biological studies2-11, the odorant-induced membrane current has remained elusive. In amphibians this current is mediated by cyclic-nucleotide-gated channels12-15, which depolarize the cell by Na+ and Ca+ influx16,17 and consequent Cl- efflux through Ca2+-dependent Cl- channels18,19. The Cl- current may be absent in mammals, however, because its proposed role is linked to the aquatic habitat of amphibians18. Here we show that the transduction current in rat olfactory receptor cells is initiated by cyclic-nucleotide-gated channels. The Cl- current is also present and endows the transduction current with a steep sigmoidal dependence on cyclic AMP concentration in both rat and in an amphibian, indicating a new function for the Cl- channel: nonlinear amplification of the transduction signal, whereby suprathreshold responses are boosted relative to basal transduction noise.