title: Viral vector-mediated expression of K+ channels regulates electrical excitability in skeletal muscle.
abstract: Modification of K+ currents by exogenous gene expression may lead to therapeutic interventions in skeletal muscle diseases characterized by alterations in electrical excitability. In order to study the specific effects of increasing outward K+ currents, we expressed a modified voltage-dependent K+ channel in primary cultured rat skeletal muscle cells. The rat Kv1.4 channel was expressed as an N-terminal fusion protein containing a bioluminescent marker (green fluorescent protein). Transgene expression was carried out using the helper-dependent herpes simplex 1 amplicon system. Transduced myoballs, identified using fluorescein optics and studied electrophysiologically with single-cell patch clamp, exhibited a greater than two-fold increase in K+ conductance by 20-30 h after infection. This increase in K+ current led to a decrease in membrane resistance and a 10-fold increase in the current threshold for action potential generation. Electrical hyperexcitability induced by the Na+ channel toxin anemone toxin II (1 microM) was effectively counteracted by overexpression of Kv1.4 at 30-32 h after transduction. Thus, virally induced overexpression of a voltage-gated K+ channel in skeletal muscle has a powerful effect in reducing electrical excitability.
authors.affiliation: Department of Physiology, College of Medicine, University of Arizona, Tucson, 85724, USA.
authors.forename: T
authors.initials: T
authors.lastname: Falk
authors.forename: R K
authors.initials: RK
authors.lastname: Kilani
authors.forename: A J
authors.initials: AJ
authors.lastname: Yool
authors.forename: S J
authors.initials: SJ
authors.lastname: Sherman
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D003064:Cnidarian Venoms / Q000494:pharmacology; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage; D049452:Green Fluorescent Proteins; D020514:Hypokalemic Periodic Paralysis / Q000503:physiopathology / Q000628:therapy*; D051665:Kv1.4 Potassium Channel; D008164:Luminescent Proteins / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000032:analysis / Q000235:genetics*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D017207:Rats, Sprague-Dawley; D018139:Simplexvirus / Q000235:genetics; D014162:Transfection / Q000379:methods
chemical_list: D003064:Cnidarian Venoms; C496979:Kcna4 protein, rat; D051665:Kv1.4 Potassium Channel; D008164:Luminescent Proteins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D049452:Green Fluorescent Proteins; C028800:toxin II (Anemonia sulcata)