Depolarization-induced alkalinization (DIA) in rat hippocampal astrocytes.
Depolarization-induced alkalinization (DIA) in rat hippocampal astrocytes.
复制标题
大鼠海马星形胶质细胞去极化诱导碱化（DIA）。
DOI：
10.1152/jn.1994.72.6.2816
复制
发表时间：
1994
影响因子：
2.5
通讯作者：
Ransom,BR
中科院分区：
文献类型：
--
作者：
Pappas,CA;Ransom,BR
1.神经胶质细胞的去极化导致其细胞内pH（pHi）增加。为了更全面地描述哺乳动物星形胶质细胞中去极化诱导的碱化（DIA），我们研究了培养的大鼠海马星形胶质细胞中的DIA。用荧光pH指示剂2 '，7'-双（羧乙基）-5，6-羧基荧光素（BCECF）装载星形胶质细胞，并使用成像系统监测pHi。从含血清培养基中取出细胞后约24小时，对其进行研究。在含3 mM K+的HCO-3缓冲液中，平均基线pHi为7.14 +/- 0.14（平均值+/- SD）。2.当浴[K+]从3增加到12 mM时，星形胶质细胞pHi迅速可逆地碱化。在HCO-3缓冲溶液中，平均DIA幅度为0.16 +/- 0.01 pH单位，平均pHi变化速率为0.076 +/- 0.03 pH单位/min。相反，在标称无HCO-3的溶液中，N-2-羟乙基哌嗪-N '-2-乙磺酸（HEPES）缓冲液的pH值要小得多（0.03 +/- 0.01 pH单位，0.04 +/- 0.01 pH单位/min; P < 0.0001），表明DIA在很大程度上是一个HCO-3依赖性过程。随后的实验在HCO-3缓冲溶液中进行。3.检查了DIA与浴[K+]中变量变化之间的关系。将浴[K+]从3 mM增加至6 mM产生0.07 +/- 0.04 pH单位的DIA，并且将[K+]降低至0.5 mM导致0.08 +/- 0.05 pH单位的酸位移。在单独的实验中通过全细胞膜片钳记录测量[K+]的这些变化对膜电位的影响。基于这些数据，可以构建Vm和pHi之间的关系;膜电位移动约10 mV导致pHi移动约0.07。4.应用0.5 mM Ba ~（2+）使Vm去极化，并在星形胶质细胞中引起DIA。这表明，在[K+]不增加的情况下，去极化可引起DIA。应用Ba 2+也阻断了K（+）诱导的DIA，可能是因为阻断K+通道阻止了K+引起的任何去极化。5.碱性基线pHis更高的细胞表现出更大和更快速的DIA。这种效应的机制尚不清楚。6.血清去除的时间影响星形胶质细胞DIA。在血清去除后约24小时研究的细胞始终表现出稳健的DIA（平均值= 0.16 +/- 0.01 pH单位）。（400字处截断摘要）
1. Depolarization of glial cells causes their intracellular pH (pHi) to increase. To more completely characterize this depolarization-induced alkalinization (DIA) in mammalian astrocytes, we studied DIA in cultured rat hippocampal astrocytes. Astrocytes were loaded with the fluorescent pH indicator 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF), and pHi was monitored with the use of an imaging system. Cells were studied approximately 24 h after removing them from serum-containing culture medium. In HCO-3-buffered solution containing 3 mM K+, mean baseline pHi was 7.14 +/- 0.14 (mean +/- SD). 2. Astrocyte pHi rapidly and reversibly alkalinized when bath [K+] was increased from 3 to 12 mM. In HCO-3-buffered solution, mean DIA amplitude was 0.16 +/- 0.01 pH units, and mean rate of pHi change was 0.076 +/- 0.03 pH units/min. In contrast, DIA elicited in nominally HCO-3-free, N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-buffered solution was much smaller (0.03 +/- 0.01 pH units, 0.04 +/- 0.01 pH units/min; P < 0.0001), indicating that DIA was, in large part, a HCO-3-dependent process. Subsequent experiments were carried out in HCO-3-buffered solution. 3. The relationship between DIA and variable changes in bath [K+] was examined. Increasing bath [K+] from 3 to 6 mM produced a DIA of 0.07 +/- 0.04 pH units, and lowering [K+] to 0.5 mM resulted in an acid shift of 0.08 +/- 0.05 pH units. The effects of these changes in [K+] on membrane potential were measured in separate experiments by whole cell patch-clamp recording. On the basis of these data, it was possible to construct a relationship between Vm and pHi; shifting membrane potential approximately 10 mV resulted in a pHi shift of approximately 0.07. 4. Application of 0.5 mM Ba2+ depolarized Vm and elicited DIA in astrocytes. This indicated that depolarization, in the absence of an increase in [K+], could cause DIA. Application of Ba2+ also blocked K(+)-induced DIA, presumably because blockade of K+ channels prevented any depolarization by K+. 5. Cells with more alkaline baseline pHis exhibited larger and more rapidly developing DIAs. The mechanism of this effect is not known. 6. The timing of serum removal affected astrocyte DIA. Cells studied approximately 24 h after serum removal always exhibited robust DIA (mean = 0.16 +/- 0.01 pH units).(ABSTRACT TRUNCATED AT 400 WORDS)