BibTeX
@MISC{Weiss_sodiumcurrents,
author = {Richard E. Weiss and Nell Sidell},
title = {Sodium Currents during Differentiation},
year = {}
}
Share
 |
 |
 |
 |
||
OpenURL
Abstract
ABSTRACT The electrophysiological properties of a human neuroblastoma cell line, LA-N-5, were studied with the whole-cell configuration of the patch clamp technique before and after the induction of differentiation by retinoic acid, a vitamin A metabolite. Action potentials could be elicited from current clamped cells before the induction of differentiation, suggesting that some neuroblasts of the developing sympathetic nervous system are excitable. The action potential upstroke was carried by a sodium conductance, which was composed of two types of sodium currents, described by their sensitivity to tetrodotoxin (T-FX) as TFX sensitive and TTX resistant. "Iq'X-sensitive and TTX-resistant sodium currents were blocked by nanomolar and micromolar concentrations of TFX, respectively. The voltage sensitivity of activation and inactivation of TTX-resistant sodium current is shifted-10 to-30 mV relative to TYX-sensitive sodium current, suggesting that TTXresistant sodium current could play a role in the initiation of action potentials. TIX-sensitive current comprised> 80 % of the total sodium current in undifferentiated LA-N-5 cells. The surface density of total sodium current increased from 24.9 to 57.8 p.A/p.F after cells were induced to differentiate. The increase in total sodium current density was significant (P < 0.05). The surface density of TTX-resistant sodium current did not change significantly during differentiation, from which we conclude that an increase in TFX-sensitive sodium current underlies the increase in total current.
Keyphrases
sodium current action potential ttx-resistant sodium surface density voltage sensitivity sodium conductance ttx resistant human neuroblastoma cell line total sodium ttxresistant sodium retinoic acid shifted-10 to-30 mv tfx-sensitive sodium undifferentiated la-n-5 cell total sodium current density action potential upstroke sympathetic nervous system patch clamp technique micromolar concentration current clamped cell whole-cell configuration electrophysiological property ttx-resistant sodium current tyx-sensitive sodium
