|
|
|
|
|
|
|
||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Address correspondence to Johannes Reisert, Department of Neuroscience, PCTB 906, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205. Fax: (410) 614 3579; email: jreisert{at}jhmi.edu
Odorants activate sensory transduction in olfactory receptor neurons (ORNs) via a cAMP-signaling cascade, which results in the opening of nonselective, cyclic nucleotide–gated (CNG) channels. The consequent Ca2+ influx through CNG channels activates Cl channels, which serve to amplify the transduction signal. We investigate here some general properties of this Ca-activated Cl channel in rat, as well as its functional interplay with the CNG channel, by using inside-out membrane patches excised from ORN dendritic knobs/cilia. At physiological concentrations of external divalent cations, the maximally activated Cl current was 
30 times as large as the CNG current. The Cl channels on an excised patch could be activated by Ca2+ flux through the CNG channels opened by cAMP. The magnitude of the Cl current depended on the strength of Ca buffering in the bath solution, suggesting that the CNG and Cl channels were probably not organized as constituents of a local transducisome complex. Likewise, Cl channels and the Na/Ca exchanger, which extrudes Ca2+, appear to be spatially segregated. Based on the theory of buffered Ca2+ diffusion, we determined the Ca2+ diffusion coefficient and calculated that the CNG and Cl channel densities on the membrane were 8 and 62 µm-2, respectively. These densities, together with the Ca2+ diffusion coefficient, demonstrate that a given Cl channel is activated by Ca2+ originating from multiple CNG channels, thus allowing low-noise amplification of the olfactory receptor current.
Key Words: olfaction • signal transduction • Ca diffusion • ion channel
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  S. J. Kleene The Electrochemical Basis of Odor Transduction in Vertebrate Olfactory Cilia Chem Senses, November 1, 2008; 33(9): 839 - 859. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. C. Hartzell, Z. Qu, K. Yu, Q. Xiao, and L.-T. Chien Molecular Physiology of Bestrophins: Multifunctional Membrane Proteins Linked to Best Disease and Other Retinopathies Physiol Rev, April 1, 2008; 88(2): 639 - 672. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Pinato, J. Rievaj, S. Pifferi, M. Dibattista, L. Masten, and A. Menini Electroolfactogram Responses from Organotypic Cultures of the Olfactory Epithelium from Postnatal Mice Chem Senses, April 1, 2008; 33(4): 397 - 404. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Takeuchi and T. Kurahashi Distribution, Amplification, and Summation of Cyclic Nucleotide Sensitivities within Single Olfactory Sensory Cilia J. Neurosci., January 16, 2008; 28(3): 766 - 775. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Boccaccio and A. Menini Temporal Development of Cyclic Nucleotide-Gated and Ca2+-Activated Cl- Currents in Isolated Mouse Olfactory Sensory Neurons J Neurophysiol, July 1, 2007; 98(1): 153 - 160. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Antolin and H. R. Matthews The effect of external sodium concentration on sodium-calcium exchange in frog olfactory receptor cells J. Physiol., June 1, 2007; 581(2): 495 - 503. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Michalakis, J. Reisert, H. Geiger, C. Wetzel, X. Zong, J. Bradley, M. Spehr, S. Huttl, A. Gerstner, A. Pfeifer, et al. Loss of CNGB1 Protein Leads to Olfactory Dysfunction and Subciliary Cyclic Nucleotide-gated Channel Trapping J. Biol. Chem., November 17, 2006; 281(46): 35156 - 35166. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Pifferi, G. Pascarella, A. Boccaccio, A. Mazzatenta, S. Gustincich, A. Menini, and S. Zucchelli Bestrophin-2 is a candidate calcium-activated chloride channel involved in olfactory transduction PNAS, August 22, 2006; 103(34): 12929 - 12934. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. B. Mazzone and A. E. McGovern Na+-K+-2Cl- cotransporters and Cl- channels regulate citric acid cough in guinea pigs J Appl Physiol, August 1, 2006; 101(2): 635 - 643. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. L. Zimmerman The Sweet Smell of Success: Conclusive Evidence that Cyclic AMP Hydrolysis Does Not Trigger Fast Adaptation in Olfactory Receptor Cells J. Gen. Physiol., July 31, 2006; 128(2): 149 - 151. [Full Text] [PDF]
|
|
|
|
|
|
A. Boccaccio, L. Lagostena, V. Hagen, and A. Menini Fast Adaptation in Mouse Olfactory Sensory Neurons Does Not Require the Activity of Phosphodiesterase J. Gen. Physiol., July 31, 2006; 128(2): 171 - 184. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. J. Flannery, D. A. French, and S. J. Kleene Clustering of Cyclic-Nucleotide-Gated Channels in Olfactory Cilia Biophys. J., July 1, 2006; 91(1): 179 - 188. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Tsunenari, J. Nathans, and K.-W. Yau Ca2+-activated Cl- Current from Human Bestrophin-4 in Excised Membrane Patches J. Gen. Physiol., May 30, 2006; 127(6): 749 - 754. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Kaneko, F. Mohrlen, and S. Frings Calmodulin Contributes to Gating Control in Olfactory Calcium-activated Chloride Channels J. Gen. Physiol., May 30, 2006; 127(6): 737 - 748. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. T. Nickell, N. K. Kleene, R. C. Gesteland, and S. J. Kleene Neuronal Chloride Accumulation in Olfactory Epithelium of Mice Lacking NKCC1 J Neurophysiol, March 1, 2006; 95(3): 2003 - 2006. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Zhang and R. J. Delay Pulse Stimulation with Odors or IBMX/Forskolin Potentiates Responses in Isolated Olfactory Neurons Chem Senses, March 1, 2006; 31(3): 197 - 206. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Reidl, P. Borowski, A. Sensse, J. Starke, M. Zapotocky, and M. Eiswirth Model of Calcium Oscillations Due to Negative Feedback in Olfactory Cilia Biophys. J., February 15, 2006; 90(4): 1147 - 1155. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Takeuchi and T. Kurahashi Mechanism of Signal Amplification in the Olfactory Sensory Cilia J. Neurosci., November 30, 2005; 25(48): 11084 - 11091. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Tomaru and T. Kurahashi Mechanisms Determining the Dynamic Range of the Bullfrog Olfactory Receptor Cell J Neurophysiol, April 1, 2005; 93(4): 1880 - 1888. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. V. Bobkov and B. W. Ache Pharmacological Properties and Functional Role of a TRP-Related Ion Channel in Lobster Olfactory Receptor Neurons J Neurophysiol, March 1, 2005; 93(3): 1372 - 1380. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Kaneko, I. Putzier, S. Frings, U. B. Kaupp, and T. Gensch Chloride Accumulation in Mammalian Olfactory Sensory Neurons J. Neurosci., September 8, 2004; 24(36): 7931 - 7938. [Abstract] [Full Text] [PDF]
|
|
|
|
