title: Role of phosphorylation and physiological state in the regulation of the muscular chloride channel ClC-1: a voltage-clamp study on isolated M. interosseus fibers.
abstract: Chloride currents (I(Cl)) were investigated with the two-electrode voltage-clamp technique in enzymatically isolated fibers from interosseus muscles of wild-type (WT), denervated WT, and myotonic (ADR, ClC-1-deficient) mice. Characteristics of I(Cl) were consistent with previous observations on rat muscle fibers and cultured nonmuscle cells transfected with hClC-1 cDNA. In the presence of 0.1 mM anthracene-9-carboxylic acid and in ADR fibers, I(Cl) was reduced by >90%. WT interosseus fibers denervated 6-7 days prior to isolation showed approximately 50% I(Cl) compared to control fibers. Addition of 3.3 microM staurosporine, a nonspecific inhibitor of protein kinases, increased I(Cl) in WT interosseus fibers by a factor of approximately two and altered its kinetic characteristics. We conclude that in dissociated fibers cultured for 1-2 days, in contrast to freshly isolated muscles, chloride conductance is downregulated by a mechanism involving protein phosphorylation. In situ, this short-term regulation may complement transcriptional long-term regulation of ClC-1.
authors.affiliation: Developmental Biology and Molecular Pathology, University of Bielefeld, Germany.
authors.forename: M F
authors.initials: MF
authors.lastname: Chen
authors.forename: H
authors.initials: H
authors.lastname: Jockusch
mesh_terms: D000818:Animals; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D003714:Denervation; D066298:In Vitro Techniques; D051379:Mice; D008817:Mice, Mutant Strains; D008855:Microscopy, Electron, Scanning; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D051381:Rats; D019311:Staurosporine / Q000494:pharmacology
chemical_list: C086321:CLC-1 channel; D018118:Chloride Channels; D019311:Staurosporine