Inhibition of voltage-dependent Na+ current in cell-fusion hybrids containing activated c-Ha-ras.
The electrophysiological properties of EJ (human bladder carcinoma), GM2291 (human fetal lung fibroblast), and of three hybrid cell lines obtained from their cell fusion were investigated using the patch-clamp technique. GM2291 cells, which are nontumorigenic, express voltage-dependent Na+ channels. The pharmacology and gating properties of the Na+ channels in GM2291 cells are distinct from neuronal and cardiac Na+ channels. EJ cells, which are tumorigenic and contain activated c-Ha-ras, express inward rectifier K+ channels. The three cell-fusion hybrid lines, named 145 (nontumorigenic), 145L (nontumorigenic but morphologically altered), and 147TR2 (fully tumorigenic segregant), have been previously shown to express levels of activated c-Ha-ras similar to those of the EJ parental line. Voltage-dependent Na+ channels were observed in none of the hybrid cell lines, while inward rectifier K+ channels were observed in each of the hybrid cell lines. The possibility that c-Ha-ras inhibits expression of a voltage-dependent Na+ channel is discussed.
Estacion
M
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Department of Physiology and Biophysics, University of California, Irvine 92717.
D002460:Cell Line; D005347:Fibroblasts; D005786:Gene Expression Regulation; D011905:Genes, ras; D006801:Humans; D006822:Hybrid Cells; D008564:Membrane Potentials; D010641:Phenotype; D015398:Signal Transduction; D015222:Sodium Channels / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms
D015222:Sodium Channels