COEXISTENCE OF CATIONIC AND CHLORIDE COMPONENTS IN ODORANT-INDUCED CURRENT OF VERTEBRATE OLFACTORY RECEPTOR-CELLS
COEXISTENCE OF CATIONIC AND CHLORIDE COMPONENTS IN ODORANT-INDUCED CURRENT OF VERTEBRATE OLFACTORY RECEPTOR-CELLS
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DOI：
10.1038/363071a0
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发表时间：
1993-05-06
期刊：
影响因子：
64.8
通讯作者：
YAU, KW
中科院分区：
文献类型：
--
作者：
KURAHASHI, T;YAU, KW
气味刺激导致嗅觉感受器神经元1-3去极化。这种转导发生在感觉纤毛3-6处，其机制涉及G蛋白介导的腺酰环化酶活性7-10的增加，因此内部环磷酸腺苷的增加，以及随后在质膜上cAMP门控阳离子通道的开放。另一种尚未确定的机制是，磷脂酶C活性24、25导致肌醇三磷酸激活的阳离子通道在血浆膜上开放。在这两种情况下，阳离子的涌入都被认为产生了去极化的受体电位。然而，我们现在报告的是，这种机制实际上更加复杂。气味诱导的电流似乎也包含一个内向的氯成分，它是由钙离子通过阳离子选择性通道内流触发的。这种新发现的氯成分可以和阳离子成分一样大。气味反应中阳离子和氯化物成分的共存可能是感觉转导机制中独一无二的，可能有助于减少由于嗅觉纤毛周围外部离子浓度变化而导致的转导电流的变化。我们的发现可以解释为什么去除大多数粘膜阳离子仍然不会降低嗅觉感受器细胞反应的幅度这一长期存在的谜题26-28。
ODORANT stimulation leads to a depolarization of olfactory receptor neurons1-3. A mechanism underlying this transduction, which occurs in the sensory cilia3-6, involves a G-protein-mediated increase in adenylyl cyclase activity7-10, and therefore a rise in internal cyclic AMP and consequent opening of a cAMP-gated cation channel on the plasma membrane11-22. Another mechanism, not as well established, involves the opening of an inositol trisphosphate-activated cation channel on the plasma membrane23 as a result of phospholipase C activity24,25. In both cases, an influx of cations is thought to generate the depolarizing receptor potential. We now report, however, that the mechanism is actually more complex. The odorant-induced current appears to contain an inward chloride component also, which is triggered by calcium influx through the cation-selective channel. This newly found chloride component can be as large as the cationic component. The co-existence of cationic and chloride components in the odorant response, possibly unique among sensory transduction mechanisms, may serve to reduce variations in the transduction current resulting from changes in external ionic concentrations around the olfactory cilia. Our finding can explain the long-standing puzzle of why removal of most mucosal cations still does not diminish the amplitude of the olfactory receptor cell response26-28.