Chronic depolarization prevents programmed death of sympathetic neurons in vitro but does not support growth: requirement for Ca2+ influx but not Trk activation
Chronic depolarization prevents programmed death of sympathetic neurons in vitro but does not support growth: requirement for Ca2+ influx but not Trk activation
复制标题
慢性去极化可防止体外交感神经元的程序性死亡，但不支持生长：需要 Ca2 流入，但不需要 Trk 激活
DOI：
10.1523/jneurosci.15-01-00643.1995
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发表时间：
1995
影响因子：
3.2
通讯作者：
Eugene M. Johnson
中科院分区：
文献类型：
--
作者：
J. Franklin;C. Sanz;A. Juhász;T. Deckwerth;Eugene M. Johnson
Continuous exposure of many types of neurons in cell culture to elevated concentrations of K+ greatly enhances their survival. This effect has been reported to be mediated by a sustained rise of cytoplasmic free Ca2+ concentration caused by influx of Ca2+ through voltage-gated channels activated by K(+)-induced chronic depolarization. In this report we investigate the effects of elevated K+ on the programmed death that embryonic rat sympathetic neurons undergo in culture when deprived of NGF. Elevated K+ in the culture medium did not significantly prevent death of NGF-deprived cells until after the third day following plating of embryonic day 21 neurons. On the fifth day after plating, incrementally increasing K+ concentrations in the culture medium from 5 to 100 mM caused chronic depolarization of neurons and had a biphasic effect on survival of NGF-deprived cells. Enhanced survival was steeply related to membrane potential, increasing from no enhanced survival in cells held at potentials between -51 and - 34 mV to 90–100% of control survival at about -21 mV. At potentials positive to -21 mV, survival decreased. Associated with the chronic depolarization was a sustained rise of steady-state free Ca2+ concentration that showed a biphasic relationship to membrane potential roughly similar to that exhibited by survival. Steady-state Ca2+ concentration increased with increasingly lower membrane potentials to a peak at about -23 mV (to approximately 240 nM from approximately 40 nM at about -51 mV) and then decreased at more positive potentials. The elevation of intracellular Ca2+ was largely blocked by dihydropyridine and phenylalkylamine Ca2+ channel antagonists and was potentiated by a dihydropyridine Ca2+ channel agonist. Neither the rise of Ca2+, or survival was affected by the Ca2+ channel antagonist, omega-conotoxin. Therefore, the Ca2+ elevation was probably caused by Ca2+ influx through L-type, but not N-type, channels. Antagonists of L channels blocked both survival and the sustained increase of steady-state free Ca2+ at similar concentrations, suggesting that the relevant factor determining survival of depolarized cells was Ca2+ influx rather than some other effect of depolarization. Surprisingly, however, there was no clear correlation between the sustained rise of Ca2+ and survival. Some membrane potentials that induced similar increases of Ca2+ concentration produced widely different levels of survival. While chronic depolarization promoted survival of neurons in the absence of NGF, cells supported in this manner showed little growth as measured by neurite extension, total cellular protein, and mean somal diameter.(ABSTRACT TRUNCATED AT 400 WORDS)
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NGF 剥夺的交感神经元程序性细胞死亡的生化特征。
DOI：
10.1002/neu.480230911
发表时间：
1992
期刊：
Journal of neurobiology
影响因子：
--
作者：
Martin,DP;Ito,A;Horigome,K;Lampe,PA;JohnsonJr,EM
通讯作者：
JohnsonJr,EM
DOI：
10.1016/s0021-9258(18)82362-6
发表时间：
1993-07
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
R. Davis
通讯作者：
R. Davis
影响因子：
56.9
作者：
KAPLAN, DR;HEMPSTEAD, BL;PARADA, LF
通讯作者：
PARADA, LF
影响因子：
56.9
作者：
GHOSH, A;CARNAHAN, J;GREENBERG, ME
通讯作者：
GREENBERG, ME
体外大鼠交感神经元多种Ca2+通道的分布。
影响因子：
3.6
作者：
Thayer,SA;Hirning,LD;Miller,RJ
通讯作者：
Miller,RJ