title: Cyclic-nucleotide-gated cation current and Ca2+-activated Cl current elicited by odorant in vertebrate olfactory receptor neurons.
abstract: Olfactory transduction in vertebrate olfactory receptor neurons (ORNs) involves primarily a cAMP-signaling cascade that leads to the opening of cyclic-nucleotide-gated (CNG), nonselective cation channels. The consequent Ca2+influx triggers adaptation but also signal amplification, the latter by opening a Ca2+-activated Cl channel (ANO2) to elicit, unusually, an inward Cl current. Hence the olfactory response has inward CNG and Cl components that are in rapid succession and not easily separable. We report here success in quantitatively separating these two currents with respect to amplitude and time course over a broad range of odorant strengths. Importantly, we found that the Cl current is the predominant component throughout the olfactory dose-response relation, down to the threshold of signaling to the brain. This observation is very surprising given a recent report by others that the olfactory-signal amplification effected by the Ca2+-activated Cl current does not influence the behavioral olfactory threshold in mice.
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: Rong-Chang
authors.initials: RC
authors.lastname: Li
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: Yair
authors.initials: Y
authors.lastname: Ben-Chaim
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205; kwyau@jhmi.edu clin2@houstonmethodist.org.
authors.forename: King-Wai
authors.initials: KW
authors.lastname: Yau
authors.affiliation: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Neuroscience Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205 kwyau@jhmi.edu clin2@houstonmethodist.org.
authors.forename: Chih-Chun
authors.initials: CC
authors.lastname: Lin
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009812:Odorants / Q000032:analysis; D018034:Olfactory Receptor Neurons / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction; D012903:Smell / Q000235:genetics / Q000502:physiology*
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D054815:Cyclic Nucleotide-Gated Cation Channels; D000242:Cyclic AMP; D002118:Calcium
keywords: calcium-activated chloride channel; cyclic-nucleotide–gated channel; olfactory receptor neurons; olfactory transduction; signal amplification