Journal article
Sarcolemmal-restricted localization of functional ClC-1 channels in mouse skeletal muscle
The Journal of general physiology, Vol.136(6), pp.597-613
12/01/2010
DOI: 10.1085/jgp.201010526
PMCID: PMC2995150
PMID: 21078869
Abstract
Skeletal muscle fibers exhibit a high resting chloride conductance primarily determined by ClC-1 chloride channels that stabilize the resting membrane potential during repetitive stimulation. Although the importance of ClC-1 channel activity in maintaining normal muscle excitability is well appreciated, the subcellular location of this conductance remains highly controversial. Using a three-pronged multidisciplinary approach, we determined the location of functional ClC-1 channels in adult mouse skeletal muscle. First, formamide-induced detubulation of single flexor digitorum brevis (FDB) muscle fibers from 15–16-day-old mice did not significantly alter macroscopic ClC-1 current magnitude (at −140 mV; −39.0 ± 4.5 and −42.3 ± 5.0 nA, respectively), deactivation kinetics, or voltage dependence of channel activation (V1/2 was −61.0 ± 1.7 and −64.5 ± 2.8 mV; k was 20.5 ± 0.8 and 22.8 ± 1.2 mV, respectively), despite a 33% reduction in cell capacitance (from 465 ± 36 to 312 ± 23 pF). In paired whole cell voltage clamp experiments, where ClC-1 activity was measured before and after detubulation in the same fiber, no reduction in ClC-1 activity was observed, despite an ∼40 and 60% reduction in membrane capacitance in FDB fibers from 15–16-day-old and adult mice, respectively. Second, using immunofluorescence and confocal microscopy, native ClC-1 channels in adult mouse FDB fibers were localized within the sarcolemma, 90° out of phase with double rows of dihydropyridine receptor immunostaining of the T-tubule system. Third, adenoviral-mediated expression of green fluorescent protein–tagged ClC-1 channels in adult skeletal muscle of a mouse model of myotonic dystrophy type 1 resulted in a significant reduction in myotonia and localization of channels to the sarcolemma. Collectively, these results demonstrate that the majority of functional ClC-1 channels localize to the sarcolemma and provide essential insight into the basis of myofiber excitability in normal and diseased skeletal muscle.
Details
- Title: Subtitle
- Sarcolemmal-restricted localization of functional ClC-1 channels in mouse skeletal muscle
- Creators
- John D Lueck - Department of Pharmacology and Physiology, and Department of Neurology, University of Rochester, Rochester, NY 14642, Department of Molecular Physiology and Biophysics, Department of Internal Medicine, Department of Neurology, and Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52246, Department of Molecular Physiology and Biophysics, Department of Internal Medicine, Department of Neurology, and Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52246Ann E Rossi - Department of Pharmacology and Physiology, and Department of Neurology, University of Rochester, Rochester, NY 14642Charles A Thornton - Department of Pharmacology and Physiology, and Department of Neurology, University of Rochester, Rochester, NY 14642Kevin P Campbell - Department of Molecular Physiology and Biophysics, Department of Internal Medicine, Department of Neurology, and Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52246, Department of Molecular Physiology and Biophysics, Department of Internal Medicine, Department of Neurology, and Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52246, Department of Molecular Physiology and Biophysics, Department of Internal Medicine, Department of Neurology, and Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52246, Department of Molecular Physiology and Biophysics, Department of Internal Medicine, Department of Neurology, and Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52246Robert T Dirksen - Department of Pharmacology and Physiology, and Department of Neurology, University of Rochester, Rochester, NY 14642
- Resource Type
- Journal article
- Publication Details
- The Journal of general physiology, Vol.136(6), pp.597-613
- DOI
- 10.1085/jgp.201010526
- PMID
- 21078869
- PMCID
- PMC2995150
- NLM abbreviation
- J Gen Physiol
- ISSN
- 0022-1295
- eISSN
- 1540-7748
- Language
- English
- Date published
- 12/01/2010
- Academic Unit
- Neurology; Molecular Physiology and Biophysics; Iowa Neuroscience Institute
- Record Identifier
- 9984020998702771
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