title: Non-genomic effects of sex hormones on CLC-1 may contribute to gender differences in myotonia congenita.
abstract: Myotonia congenita is caused by mutations in the voltage-gated chloride channel ClC-1. It is more severe in men than women and often worsens during pregnancy, but the basis for these gender differences is not known. We show here that both testosterone and progesterone rapidly and reversibly inhibit wild-type ClC-1 channels expressed in Xenopus oocytes by causing a prominent rightward shift in the voltage dependence of their open probability. In contrast, 17beta-estradiol at similar concentrations causes only a small shift. Progesterone and testosterone also profoundly inhibit ClC-1 channels containing the mutation F297S associated with dominantly inherited myotonia congenita. The effects of sex hormones are likely to be non-genomic because of their speed of onset and reversibility. These results suggest a possible mechanism to explain how the severity of myotonia congenita can be modulated by sex hormones.
authors.affiliation: MRC Centre for Neuromuscular Disease, UCL Institute of Neurology and National Hospital for Neurology, Queen Square, London WC1N 3BG, UK.
authors.forename: Doreen
authors.initials: D
authors.lastname: Fialho
authors.forename: Dimitri M
authors.initials: DM
authors.lastname: Kullmann
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hanna
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schorge
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018118:Chloride Channels / Q000235:genetics / Q000502:physiology*; D004566:Electrodes; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D005260:Female; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009224:Myotonia Congenita / Q000235:genetics / Q000503:physiopathology*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000295:instrumentation / Q000379:methods; D011374:Progesterone / Q000494:pharmacology*; D012737:Sex Factors; D013739:Testosterone / Q000494:pharmacology*; D014981:Xenopus
chemical_list: C086321:CLC-1 channel; D018118:Chloride Channels; D013739:Testosterone; D011374:Progesterone