Analysis of Na+/Ca2+ exchange activity in human brain: the effect of normal aging.
Analysis of Na+/Ca2+ exchange activity in human brain: the effect of normal aging.
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人脑Na/Ca2交换活性分析：正常衰老的影响。
DOI：
10.1016/0197-4580(93)90124-t
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发表时间：
1993
影响因子：
4.2
通讯作者：
Murphy,CA
中科院分区：
文献类型：
--
作者：
Colvin,RA;Wu,A;Davis,N;Murphy,CA
研究了从大鼠全脑和人脑额叶皮质、颞叶皮质和小脑三个区域纯化的质膜泡（PMV）的Na+/Ca2+交换活性和对Ca2+的被动通透性。由于Na+/Ca2+交换活性引起的Ca2+积累在大鼠和人脑中都表现出Ca2+含量最初快速上升的特征模式，随后是稳定的平台期。大鼠脑PMV中Ca2+总积累量平均比人脑高3倍。通过Na+/Ca2+交换，PMV首先装载45ca，然后暴露于1mm EGTA，通过测量PMV对Ca2+的被动通透性来释放Ca2+。人和大鼠脑PMV的Ca2+通透性相似。大鼠脑PMV的Ca2+释放总体上更快，并分解为快速和慢速组分，而在人脑中发现单一的慢速组分。死后延迟4小时对大鼠脑PMV中Na+/Ca2+交换Km、Vmax、峰值摄取和Ca2+释放率没有影响。人类额叶皮层显示出比小脑更大的Na+/Ca2+交换活性。额叶皮质、颞叶皮质和小脑具有相似的Ca2+通透性。年龄对Na+Ca2+交换活性和Ca2+通透性的影响在人类额叶皮层的15个组织中被确定（死亡年龄21至93岁）。没有发现明显的年龄相关影响。这些数据不排除Ca2+稳态的丧失是正常大脑衰老的一个组成部分，但确实表明Na+/Ca2+交换活性和Ca2+通透性的显著变化并不伴随着正常的人类大脑衰老。
Na+/Ca2+exchange activity and passive permeability to Ca2+were analyzed in plasma membrane vesicles (PMV) purified from whole rat brain and three regions of human brain: frontal cortex, temporal cortex, and cerebellum. Accumulation of Ca2+due to Na+/Ca2+exchange activity showed a characteristic pattern of an initial rapid rise in Ca2+content followed by a stable plateau in both rat and human brain. Total Ca2+accumulation in rat brain PMV was on average three-fold higher than in human brain. Passive permeability to Ca2+was measured as the rate of Ca2+release from PMV first loaded with45Ca by Na+/Ca2+exchange and then exposed to 1 mM EGTA. The Ca2+permeabilities of human and rat brain PMV were similar. Ca2+release from rat brain PMV was faster overall and was resolved into fast and slow components while in human brain a single slow component was found. Post mortem delay up to 4 h had no effect on Na+/Ca2+exchange Km for Ca2+, Vmax, and peak uptake and Ca2+release rate in rat brain PMV. Human frontal cortex was shown to have a greater Na+/Ca2+exchange activity than that found in the cerebellum. The frontal cortex, temporal cortex and cerebellum had similar Ca2+permeabilities. Age-related effects on Na+Ca2+exchange activity and Ca2+permeability were determined in 15 tissues from human frontal cortex (age at death 21 to 93 years). No significant age related effects were seen. These data do not rule out the loss of Ca2+homoestasis as a component of normal brain aging but do indicate that significant changes in Na+/Ca2+exchange activity and Ca2+permeability do not accompany normal human brain aging.