In:
European Journal of Neuroscience, Wiley, Vol. 10, No. 8 ( 1998-08), p. 2532-2546
Abstract:
Resting membrane potential (RMP), K + channel contribution to RMP and the development of excitability were investigated in the entire population of acutely dissociated embryonic (E) rat cortical cells over E11–22 using a voltage‐sensitive fluorescent indicator dye and flow cytometry. During the period of intense proliferation (E11–13), two cell subpopulations with distinct estimated RMPs were recorded: one polarized at ∼–70 mV and the other relatively less‐polarized at ∼–40 mV. Ca 2+ o was critical in sustaining the RMP of the majority of less‐polarized cells, while the well‐polarized cells were characterized by membrane potentials exhibiting a ∼Nernstian relationship between RMP and [K + ] o . Analysis of these two subpopulations revealed that 〉 80% of less‐polarized cells were proliferative, while 〉 90% of well‐polarized cells were postmitotic. Throughout embryonic development, the disappearance of Ca 2+ o ‐sensitive, less‐polarized cells correlated with the disappearance of the proliferating population, while the appearance of the K + o ‐sensitive, well‐polarized population correlated with the appearance of terminally postmitotic neurons, immuno‐identified as BrdU – , tetanus toxin + cells. Differentiating neurons were estimated to contain increased K + i relative to less‐polarized cells, coinciding with the developmental expression of Cs + /Ba 2+ ‐sensitive and Ca 2+ ‐dependent K + channels. Both K + channels contributed to the RMP of well‐polarized cells, which became more negative toward the end of neurogenesis. Depolarizing effects of veratridine, first observed at E11, progressively changed from Ca 2+ o ‐dependent and tetrodotoxin‐insensitive to Na + o ‐dependent and tetrodotoxin‐sensitive response by E18. The results reveal a dynamic development of RMP, contributing K + channels and voltage‐dependent Na + channels in the developing cortex as it transforms from proliferative to primarily differentiating tissue.
Type of Medium:
Online Resource
ISSN:
0953-816X
,
1460-9568
DOI:
10.1046/j.1460-9568.1998.00284.x
Language:
English
Publisher:
Wiley
Publication Date:
1998
detail.hit.zdb_id:
2005178-5
SSG:
12
