Transfection of activated ras into an excitable cell line (AtT-20) alters tetrodotoxin sensitivity of voltage-dependent sodium current.
The sensitivity of voltage-dependent sodium current to the sodium channel blocker tetrodotoxin (TTX) is altered by transfection of a c-Ha-ras oncogene into an excitable cell line. Control AtT-20 cells, a cell line derived from a mouse anterior pituitary tumor, were found to express both a TTX-sensitive and a TTX-resistant sodium current. AtT-20 cells transfected with the c-Ha-ras gene expressed only a TTX-sensitive current. Properties of TTX-sensitive and -resistant currents were also examined. No differences in voltage dependence of activation or inactivation between the TTX-sensitive and -resistant currents were observed. The rate of inactivation of the TTX-resistant current in control cells was slower, than that of the TTX-sensitive current in either control or ras-transfected AtT-20 cells.
Flamm
R E
RE
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06510-8066.
Birnberg
N C
NC
Kaczmarek
L K
LK
D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance / Q000235:genetics; D004553:Electric Conductivity; D011905:Genes, ras; D006801:Humans; D010903:Pituitary Gland, Anterior; D010911:Pituitary Neoplasms; D012964:Sodium / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured
D013779:Tetrodotoxin; D012964:Sodium