Disrupted [Ca2+]i homeostasis contributes to the toxicity of nitric oxide in cultured hippocampal neurons.
Disrupted [Ca2+]i homeostasis contributes to the toxicity of nitric oxide in cultured hippocampal neurons.
复制标题
[Ca2]i 稳态的破坏会导致培养的海马神经元中一氧化氮的毒性。
DOI：
10.1046/j.1471-4159.1997.69051882.x
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发表时间：
1997
影响因子：
4.7
通讯作者：
Zhang,H
中科院分区：
文献类型：
--
作者：
Brorson,JR;Zhang,H
一氧化氮(NO)已被证明是几种形式的神经毒性的重要介体。我们先前报道，在20分钟的暴露中，NO改变培养的海马神经元细胞内钙浓度([Ca~(2+)]i)的动态平衡。在本研究中，我们研究了细胞内钙离子稳态的晚期改变与NO产生的迟发性毒性之间的关系。NO释放剂亚硝基半胱氨酸(SNOC；300µM)与其他NO释放剂一样，在暴露20分钟后使存活率减少约半天。NO清除剂血红蛋白可阻断SNOC的迟发性[Ca~(2+)]i升高和延迟性毒性作用。在SNOC处理20分钟期间清除细胞外钙离子不能阻止后期的[Ca~(2+)]升高，也不能阻止延迟毒性，但在暴露后6小时内清除细胞外Ca~(2+)也能阻断大部分毒性。Western blotts显示，暴露于SNOC导致结构蛋白光谱蛋白的蛋白分解增加，产生了一段具有免疫反应性的片段，表明钙激活的蛋白酶Calain的活性。钙蛋白酶拮抗剂可抑制幽灵蛋白的降解和SNOC的毒性作用。我们的结论是，暴露于毒性水平的NO会导致[Ca~(2+)]稳态机制的长期破坏，由此产生的持续性[Ca~(2+)]升高是NO迟发性神经毒性的原因之一。
Nitric oxide (NO) has been shown to be an important mediator in several forms of neurotoxicity. We previously reported that NO alters intracellular Ca2+concentration ([Ca2+]i) homeostasis in cultured hippocampal neurons during 20‐min exposures. In this study, we examine the relationship between late alterations of [Ca2+]ihomeostasis and the delayed toxicity produced by NO. The NO‐releasing agentS‐nitrosocysteine (SNOC; 300 µM) reduced survival by about one half 1 day after 20‐min exposures, as did other NO‐releasing agents. SNOC also was found to produce prolonged elevations of [Ca2+]i, persisting at 2 and 6 h. Hemoglobin, a scavenger of NO, blocked both the late [Ca2+]ielevation and the delayed toxicity of SNOC. Removal of extracellular Ca2+during the 20‐min SNOC treatment failed to prevent the late [Ca2+]ielevations and did not prevent the delayed toxicity, but removal of extracellular Ca2+for the 6 h after exposure as well blocked most of the toxicity. Western blots showed that SNOC exposure resulted in an increased proteolytic breakdown of the structural protein spectrin, generating a fragment with immunoreactivity suggesting activity of the Ca2+‐activated protease calpain. The spectrin breakdown and the toxicity of SNOC were inhibited by treatment with calpain antagonists. We conclude that exposures to toxic levels of NO cause prolonged disruption of [Ca2+]ihomeostatic mechanisms, and that the resulting persistent [Ca2+]ielevations contribute to the delayed neurotoxicity of NO.