Concentration dependence of sodium permeation and sodium ion interactions in the cyclic AMP-gated channels of mammalian olfactory receptor neurons

Balasubramanian, S, Lynch, JW and Barry, PH (1997) Concentration dependence of sodium permeation and sodium ion interactions in the cyclic AMP-gated channels of mammalian olfactory receptor neurons. Journal of Membrane Biology, 159 1: 41-52. doi:10.1007/s002329900267


Author Balasubramanian, S
Lynch, JW
Barry, PH
Title Concentration dependence of sodium permeation and sodium ion interactions in the cyclic AMP-gated channels of mammalian olfactory receptor neurons
Journal name Journal of Membrane Biology   Check publisher's open access policy
ISSN 0022-2631
Publication date 1997-01-01
Year available 1997
Sub-type Article (original research)
DOI 10.1007/s002329900267
Open Access Status Not yet assessed
Volume 159
Issue 1
Start page 41
End page 52
Total pages 12
Place of publication NEW YORK
Publisher SPRINGER VERLAG
Language eng
Abstract The dependence of currents through the cyclic nucleotide-gated (CNG) channels of mammalian olfactory receptor neurons (ORNs) on the concentration of NaCl was studied in excised inside-out patches from their dendritic knobs using the patch-clamp technique. With a saturating concentration (100 mu M) of adenosine 3', 5'-cyclic monophosphate (cAMP), the changes in the reversal potential of macroscopic currents were studied at NaCl concentrations from 25 to 300 mM. In symmetrical NaCl solutions without the addition of divalent cations, the current-voltage relations were almost linear, reversing close to O mV. When the external NaCl concentration was maintained at 150 mM and the internal concentrations were varied, the reversal potentials of the cAMP-activated currents closely followed the Na+ equilibrium potential indicating that P-Cl/P-Na approximate to 0. However, at low external NaCl concentrations (less than or equal to 100 mM) there was some significant chloride permeability. Our results further indicated that Na+ currents through these channels: (i) did not obey the independence principle; (ii) showed saturation kinetics with K(m)s in the range of 100-150 mM and (iii) displayed a lack of voltage dependence of conductance in asymmetric solutions that suggested that ion-binding sites were situated midway along the channel. Together, these characteristics indicate that the permeation properties of the olfactory CNG channels are significantly different from those of photoreceptor CNG channels.
Keyword Biochemistry & Molecular Biology
Cell Biology
Physiology
Olfactory Receptor Neuron
Dendritic Knob
Cyclic Amp
Cyclic Nucleotide-gated Channel
Cation Permeation
Concentration Effects
Monovalent Cations
Organic Cations
Patch-clamp
Selectivity
Cells
Photoreceptors
Conductance
Activation
Salamander
Junction
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biomedical Sciences Publications
 
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Created: Tue, 14 Aug 2007, 02:57:22 EST