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Title: Neuronal expression of an FMRFamide-gated Na+ channel and its modulation by acid pH
Authors: Perry, S.J.
Straub, Volko A.
Schofield, M.G.
Burke, J.F.
Benjamin, P.R.
First Published: 2001
Publisher: Society for Neuroscience
Citation: Journal of Neuroscience, 2001, 21 (15), pp.5559-5567
Abstract: The molluscan Phe-Met-Arg-Phe-amide (FMRFamide)-gated sodium channels (FaNaCs) show both structural and functional similarities to the mammalian acid-sensing ion channels (ASICs). Both channel types are related to the epithelial sodium channels and, although the neuropeptide FMRFamide directly gates the FaNaCs, it also modulates the proton-gating properties of ASICs. It is not yet known whether protons can alter the gating properties of the FaNaCs. We chose to examine this possibility at a site of FaNaC expression in the nervous system of the mollusk Lymnaea stagnalis. We cloned a putative L. stagnalis FaNaC (LsFaNaC) that exhibited a high degree of sequence identity to the Helix aspersa FaNaC (HaFaNaC, 60%), and a weaker homology to the ASICs (ASIC3, 22%). In situ hybridization was used to map the LsFaNaC expression pattern in the brain and to identify the right pedal giant1 (RPeD1) neuron as a site where the properties of the endogenous channel could be studied. In RPeD1 neurons isolated in culture, we demonstrated the presence of an FMRFamide-gated sodium current with features expected for a FaNaC: amiloride sensitivity, sodium selectivity, specificity for FMRFamide and Phe-Leu-Arg-Phe-amide (FLRFamide), and no dependency on G-protein coupling. The sodium current also exhibited rapid desensitization in response to repeated FMRFamide applications. Lowering of the pH of the bathing solution reduced the amplitude of the FMRFamide-gated inward current, while also activating an additional sustained weak inward current that was apparently not mediated by the FaNaC. Acidification also prevented the desensitization of the FMRFamide-induced inward current. The acid sensitivity of LsFaNaC is consistent with the hypothesis that FaNaCs share a common ancestry with the ASICs
ISSN: 0270-6474
eISSN: 1529-2401
Version: Publisher version
Status: Peer reviewed
Type: Article
Rights: Copyright © 2001 Society for Neuroscience. Deposited with reference to the publisher's archiving policy available on the SHERPA/RoMEO website. 6 months after publication the work becomes available to the public to copy, distribute, or display under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license.
Appears in Collections:Published Articles, Dept. of Cell Physiology and Pharmacology

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