Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/35560
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Type: Journal article
Title: Inhibition of mechanosensitivity in vsceral primary afferents by gaba b receptors involves calcium and potassium channels
Author: Page, A.
O'Donnell, T.
Blackshaw, L.
Citation: Neuroscience, 2006; 137(2):627-636
Publisher: Pergamon-Elsevier Science Ltd
Issue Date: 2006
ISSN: 0306-4522
1873-7544
Abstract: GABA(B) receptors inhibit mechanosensitivity of visceral afferents. This is associated with reduced triggering of events that lead to gastro-esophageal reflux, with important therapeutic consequences. In other neuronal systems, GABA(B) receptor activation may be linked via G-proteins to reduced N-type Ca(2+) channel opening, increased inward rectifier K(+) channel opening, plus effects on a number of intracellular messengers. Here we aimed to determine the role of Ca(2+) and K(+) channels in the inhibition of vagal afferent mechanoreceptor function by the GABA(B) receptor agonist baclofen. The responses of three types of ferret gastro-esophageal vagal afferents (mucosal, tension and tension mucosal receptors) to graded mechanical stimuli were investigated in vitro. The effects of baclofen (200 microM) alone on these responses were quantified, and the effects of baclofen in the presence of the G-protein-coupled inward rectifier potassium channel blocker Rb(+) (4.7 mM) and/or the N-type calcium channel blocker omega-conotoxin GVIA (0.1 microM). Baclofen inhibition of mucosal receptor mechanosensitivity was abolished by both blockers. Its inhibitory effect on tension mucosal receptors was partly reduced by both. The inhibitory effect of baclofen on tension receptors was unaffected. The data indicate that the inhibitory action of GABA(B) receptors is mediated via different pathways in mucosal, tension and tension mucosal receptors via mechanisms involving both N-type Ca(2+) channels and inwardly rectifying K(+) channels and others.
Keywords: Gastrointestinal Tract; Esophagus; Stomach; Gastric Mucosa; Visceral Afferents; Neurons, Afferent; Mechanoreceptors; Animals; Ferrets; gamma-Aminobutyric Acid; Baclofen; Calcium Channels; Calcium Channels, N-Type; Potassium Channels; Potassium Channels, Inwardly Rectifying; Receptors, GABA-B; GABA Agonists; Potassium Channel Blockers; Calcium Signaling; Action Potentials; Neural Inhibition
Description: Copyright © 2005 IBRO Published by Elsevier Ltd.
RMID: 0020063129
DOI: 10.1016/j.neuroscience.2005.09.016
Appears in Collections:Molecular and Biomedical Science publications

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