title: Disruption of actin filaments increases the activity of sodium-conducting channels in human myeloid leukemia cells.
abstract: With the use of the patch clamp technique, the role of cytoskeleton in the regulation of ion channels in plasma membrane of leukemic K562 cells was examined. Single-channel measurements have indicated that disruption of actin filaments with cytochalasin D (CD) resulted in a considerable increase of the activity of non-voltage-gated sodium-permeable channels of 12 pS unitary conductance. Background activity of these channels was low; open probability (po) did not exceed 0.01-0.02. After CD, po grew at least 10-20 times. Cell-attached and whole-cell recordings showed that activation of sodium channels was elicited within 1-3 min after the addition of 10-20 micrograms/ml CD to the bath extracellular solution or in the presence of 5 micrograms/ml CD in the intracellular pipette solution. Preincubation of K562 cells with CD during 1 h also increased drastically the activity of 12 pS sodium channels. Whole-cell measurements confirmed that CD-activated channels were permeable to monovalent cations (preferentially to Na+ and Li+), but not to bivalent cations (Ca2+, Ba2+). Colchicine (1 microM), which affect microtubules, did not alter background channel activity. Our data indicate that actin filaments organization plays an important role in the regulation of sodium-permeable channels which may participate in providing passive Na+ influx in red blood cells.
authors.affiliation: Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia.
authors.forename: Y A
authors.initials: YA
authors.lastname: Negulyaev
authors.forename: E A
authors.initials: EA
authors.lastname: Vedernikova
authors.forename: A V
authors.initials: AV
authors.lastname: Maximov
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects*; D000199:Actins; D002463:Cell Membrane Permeability / Q000187:drug effects; D015638:Cytochalasin D / Q000494:pharmacology*; D004594:Electrophysiology; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology; D018408:Patch-Clamp Techniques; D015222:Sodium Channels / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D000199:Actins; D015222:Sodium Channels; D015638:Cytochalasin D