title: Enhancement of voltage-gated Na+ channel current associated with multidrug resistance in human leukemia cells.
abstract: Membrane currents were examined in a drug-sensitive human leukemia cell line (K562) and its multidrug-resistant cell line (K562/ADM) under the whole-cell variation of the patch electrode voltage clamp technique. Most K562 cells showed only the outward current, which was completely suppressed by internal Cs+ ions and 20 mM ethyleneglycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. In contrast to K562 cells, most K562/ADM cells showed tetrodotoxin-sensitive, voltage-gated Na+ channel current in addition to the outward current. Na+ current was observed in four of 29 K562 cells examined, while it was observed in 29 of 33 K562/ADM cells. Two revertant cell lines (R1-3, R1-5) did not show Na+ current. It was concluded that the amplitude of voltage-gated Na+ current increases in association with multidrug resistance in human leukemia cells.
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002460:Cell Line; D004317:Doxorubicin / Q000627:therapeutic use; D004351:Drug Resistance; D004533:Egtazic Acid / Q000494:pharmacology; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D007938:Leukemia / Q000188:drug therapy*; D008433:Mathematics; D008564:Membrane Potentials / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014748:Vinca Alkaloids / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; D007473:Ion Channels; D014748:Vinca Alkaloids; D013779:Tetrodotoxin; D004533:Egtazic Acid; D004317:Doxorubicin; D012964:Sodium