Voltage-clamp study of calcium currents during differentiation in the NCB-20 neuronal cell line.
1. Calcium currents (ICa) were studied in voltage-clamped NCB-20 cells. In undifferentiated cells, voltage steps from hyperpolarized potentials (-80/-100 mV) essentially revealed transient ICa showing characteristics classically described for "T-type" channels. In about 50% of the cells, there was a residual current at the end of the step; no ICa was elicited from a holding potential of -50 mV. 2. In contrast, 100% of the cells differentiated with dibutyryl cyclic AMP (cAMP) displayed a residual current in addition to the transient one, and depolarizing steps from a holding potential of -50 mV induced a sustained current. In these cells, Bay K 8644 elicited both a negative shift in voltage dependence and a moderate increase of the sustained component. 3. Although these changes in Ca2+ channel physiology result from chemically induced differentiation, they might not be directly related to the concomitant morphologic differentiation. 4. In undifferentiated NCB-20 cells, T-type Ca2+ currents can be elicited in relative isolation.
Mienville
J M
JM
SANOFI Recherche, Montpellier, France.
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D006822:Hybrid Cells; D015640:Ion Channel Gating / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured
D015220:Calcium Channels; D003994:Bucladesine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002118:Calcium