Elevated levels of glucose and L-fucose reduce 22Na+ uptake and whole cell Na+ current in cultured neuroblastoma cells.
Na+ flux was studied in cultured neuroblastoma cells grown in medium containing increased glucose or L-fucose concentrations. Chronic exposure of neuroblastoma cells to 30 mM glucose or 30 mM L-fucose caused a decrease in ouabain-sensitive and veratridine-stimulated 22Na+ uptake compared with cells cultured in unsupplemented medium. The Na+ current, determined by using whole-cell configuration of the patch clamp, was also decreased in these cells. Tetrodotoxin (3 microM), which blocked whole cell Na+ currents, also blocked veratridine-stimulated 22Na+ accumulation. Culturing cells in medium containing 30 mM fructose as an osmotic control had no effect on Na+ flux. Specific [3H]saxitoxin binding was not affected by 30 mM glucose or 30 mM L-fucose compared with cells grown in unsupplemented medium, suggesting that the number of Na+ channels was not decreased. These studies suggest that exposing cultured neuronal cells to conditions that occur in the diabetic milieu alters Na+ transport and Na(+)-channel activity.
Yorek
M A
MA
Veterans Administration Medical Center, Department of Internal Medicine, Iowa City, IA 52246.
Stefani
M R
MR
Wachtel
R E
RE
D000818:Animals; D002455:Cell Division; D002460:Cell Line; D004558:Electric Stimulation; D005643:Fucose / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D012530:Saxitoxin / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D012979:Sodium Radioisotopes; D014407:Tumor Cells, Cultured; D014701:Veratridine / Q000494:pharmacology
D015222:Sodium Channels; D012979:Sodium Radioisotopes; D005643:Fucose; D012530:Saxitoxin; D010042:Ouabain; D014701:Veratridine; D012964:Sodium; D005947:Glucose