Premium
Different voltage‐gated sodium currents are expressed by human neuroblastoma NB69 cells when cultured in defined serum‐free and in astroglial‐conditioned media
Author(s) -
Urbano Francisco J.,
Sierra Felipe,
Colombo Jorge A.,
Velasco Jose M.,
Buño Washington
Publication year - 1997
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199702)19:2<161::aid-glia7>3.0.co;2-3
Subject(s) - tetrodotoxin , biology , patch clamp , biophysics , neuroblastoma , sodium channel , sodium , microbiology and biotechnology , endocrinology , cell culture , chemistry , electrophysiology , neuroscience , genetics , organic chemistry
Voltage‐gated Na + currents (I Na ) were analysed with the whole‐cell patch‐clamp technique in human neuroblastoma NB69 cells plated in serum‐free “defined” medium (DM) or in “astroglial‐conditioned” medium (CM). Cells survived in both media and expressed the microtubule associated protein 1A, indicating neuron‐like differentiation. Two I Na types with different time‐, voltage‐dependent properties and tetrodotoxin (TTX) sensitivities were expressed in DM and CM. The I Na in DM‐plated cells was present from day 4 and its surface density increased from 11 pA/pF (days 5–7) to 68 pA/pF (days 15–30). The underlying conductance (G Na ) half‐activated (V 0A ) at −24 mV. I Na inactivation was fitted by single exponentials with 7.5 ms time constant (t h ) at the −35 mV half‐inactivation voltage (V 0I ). I Na was not affected by 10 nM, was reduced (65%) by 100 nM, and not completely abolished (92%) by 300 nM tetrodotoxin (TTX). The I Na of CM‐plated cells appeared at day 3–4 and its surface density increased from 14 pA/pF (days 3–6) to 28 pA/pF (days 11–14). The G Na V 0A was −29 mV and inactivation was fitted by single exponentials with 2.6 ms t h at the −58 mV V 0I . This I Na was reduced (55%) by 10 nM and totally abolished by 100 nM tetrodotoxin (TTX). In conclusion, NB69 cells displayed a slow, “TTX‐resistant,” or a fast, “TTX‐sensitive” I Na in DM and CM, respectively, suggesting that the CM contained diffusible trophic factors of astroglial origin that induced the expression of a different Na + channel type. About half of the CM‐ and DM‐plated cells also displayed a persistent Na + current (I NaP ). © 1997 Wiley‐Liss Inc.