title: Altered gating and conductance of Na+ channels in hyperkalemic periodic paralysis.
abstract: Electrophysiological studies on muscle fibres from patients with hyperkalemic periodic paralysis with myotonia have shown that the episodes of weakness are caused by a sustained depolarization of the sarcolemma to potentials between -40 and -60 mV. In muscle fibre segments from three such patients this sustained depolarization was caused by noninactivating Na+ channels with reduced single-channel conductance blocked by TTX and procainamide. As the chloride conductance was normal, myotonia may be best explained with the abnormal reopenings of the Na+ channels. The recently described genetic linkage between hyperkalemic periodic paralysis with myotonia and the gene coding for the TTX-sensitive Na+ channel suggests an altered primary structure of this channel causing its abnormal function.
authors.affiliation: Neurologische Klinik, Technischen Universität München, Federal Republic of Germany.
authors.forename: F
authors.initials: F
authors.lastname: Lehmann-Horn
authors.forename: P A
authors.initials: PA
authors.lastname: Iaizzo
authors.forename: H
authors.initials: H
authors.lastname: Hatt
authors.forename: C
authors.initials: C
authors.lastname: Franke
mesh_terms: D004553:Electric Conductivity; D006801:Humans; D006947:Hyperkalemia / Q000150:complications / Q000503:physiopathology*; D015640:Ion Channel Gating / Q000502:physiology*; D008564:Membrane Potentials; D009132:Muscles / Q000503:physiopathology*; D010245:Paralyses, Familial Periodic / Q000150:complications / Q000503:physiopathology*; D011342:Procainamide / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D015222:Sodium Channels; D013779:Tetrodotoxin; D011342:Procainamide