Novel expression of a functional glycine receptor chloride channel that attenuates contraction in airway smooth muscle.

Bibliographic Collection: 
MOCA Reference, APE
Publication Type: Journal Article
Authors: Yim, Peter D; Gallos, George; Xu, Dingbang; Zhang, Yi; Emala, Charles W
Year of Publication: 2011
Journal: FASEB J
Volume: 25
Issue: 5
Pagination: 1706-17
Date Published: 05/2011
Publication Language: eng
ISSN: 1530-6860
Keywords: Acetylcholine, Animals, Cells, Cultured, Cesium, Chlorides, Electrophysiology, Glycine, Guinea Pigs, Humans, Immunoblotting, Isoproterenol, Membrane Potentials, Muscle Contraction, Muscle Relaxation, Muscle, Smooth, Neurokinin A, Receptors, Glycine, Respiratory System, Reverse Transcriptase Polymerase Chain Reaction, Strychnine

Airway smooth muscle (ASM) contraction is an important component of the pathophysiology of asthma. Taurine, an agonist of glycine receptor chloride (GlyR Cl(-)) channels, was found to relax contracted ASM, which led us to question whether functional GlyR Cl(-) channels are expressed in ASM. Messenger RNA for β (GLRB), α1 (GLRA1), α2 (GLRA2), and α4 (GLRA4) subunits were found in human (Homo sapiens) and guinea pig (Cavia porcellus) tracheal smooth muscle. Immunoblotting confirmed the protein expression of GLRA1 and GLRB subunits in ASM. Electrical activity of cultured human ASM cells was assessed using a fluorescent potentiometric dye and electrophysiological recordings. Glycine increased current and significantly increased fluorescence in a dose-dependent manner. The GlyR Cl(-) channel antagonist strychnine significantly blocked the effects of glycine on potentiometric fluorescence in ASM cells. Guinea pig airway ring relaxation of ACh-induced contractions by isoproterenol was significantly left-shifted in the presence of glycine. This effect of glycine was blocked by pretreatment with the GlyR Cl(-) channel antagonist strychnine. Glycine treatment during tachykinin- and acetylcholine-induced contractions significantly decreased the maintenance of muscle force compared to control. GlyR Cl(-) channels are expressed on ASM and regulate smooth muscle force and offer a novel target for therapeutic relaxation of ASM.

DOI: 10.1096/fj.10-170530
Alternate Journal: FASEB J.
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