Intracellular pH Regulation in Cultured Astrocytes from Rat Hippocampus
Intracellular pH Regulation in Cultured Astrocytes from Rat Hippocampus
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大鼠海马培养星形胶质细胞的细胞内 pH 调节
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
W. Boron
中科院分区：
文献类型：
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作者：
M. O. Bevensee;R. A. Weed;W. Boron
本研究利用2′，7′-双羧基乙基-5,6-羧基荧光素（BCECF）监测大鼠海马单培养星形胶质细胞对细胞内pH （pHi）的调节。固有缓冲能力（βI）在pHi 7.0时为10.5 mM （pH单位）−1，随pHi值线性降低；数据的最佳拟合线斜率为- 10.0 mM （pH单位）- 2。在没有HCO3−的情况下，从酸负荷中回收pHi主要由Na-H交换剂介导，因为在pHi为6.05时，阿米洛林的回收率为88%，乙基异丙基胺洛林（EIPA）的回收率为79%。酸挤压的乙基异丙基酰胺敏感组分随pHi呈线性下降。用Li+代替Na+可抑制酸挤压68% （pHi 6.23）。由于Na+驱动的HCO3 -转运体的作用，从无CO2/HCO3−切换到含CO2/HCO3−的镀液中，平均稳态pHi从6.82增加到6.90。amiloride不影响HCO3−诱导的pHi升高，但400 μM - 4,4 ' -异硫氰化二苯乙烯-2,2 ' -二磺酸（DIDS）可抑制75% (pHi 6.85)， 400 μM -4 -乙酰氨基-4 ' -异硫氰化二苯乙烯-2,2 ' -二磺酸（SITS）预处理星形胶质细胞长达6.3 h可抑制65% （pHi 6.55-6.75）。用n -甲基-d-葡萄糖铵（NMDG+）取代Na+后，CO2/HCO3−诱导的pHi升高被阻断。在HCO3−存在的情况下，Na+驱动的HCO3−转运体有助于从酸负荷中恢复pHi。例如，HCO3使酸挤压率与pHi曲线向碱性方向偏移了0.15-0.3个pH单位。此外，由于氨酰抑制了Na-H交换，HCO3−酸挤压增加了3.8倍（pHi 6.20）。当星形胶质细胞在阿米洛利酸中加载时，以Li+为主要阳离子，HCO3−不能引起pHi的显著增加。因此，Li+似乎不能很好地替代HCO3−转运体上的Na+。我们得出结论，在星形胶质细胞中，钠离子敏感的Na- h交换器和Na+驱动的HCO3 -转运体是主要的酸挤出剂。
We studied the regulation of intracellular pH (pHi) in single cultured astrocytes passaged once from the hippocampus of the rat, using the dye 2′,7′-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) to monitor pHi. Intrinsic buffering power (βI) was 10.5 mM (pH unit)−1 at pHi 7.0, and decreased linearly with pHi; the best-fit line to the data had a slope of −10.0 mM (pH unit)−2. In the absence of HCO3 −, pHi recovery from an acid load was mediated predominantly by a Na-H exchanger because the recovery was inhibited 88% by amiloride and 79% by ethylisopropylamiloride (EIPA) at pHi 6.05. The ethylisopropylamiloride-sensitive component of acid extrusion fell linearly with pHi. Acid extrusion was inhibited 68% (pHi 6.23) by substituting Li+ for Na+ in the bath solution. Switching from a CO2/HCO3 −-free to a CO2/HCO3 −-containing bath solution caused mean steady state pHi to increase from 6.82 to 6.90, due to a Na+-driven HCO3 − transporter. The HCO3 −-induced pHi increase was unaffected by amiloride, but was inhibited 75% (pHi 6.85) by 400 μM 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), and 65% (pHi 6.55–6.75) by pretreating astrocytes for up to ∼6.3 h with 400 μM 4-acetamide-4′-isothiocyanatostilbene-2,2′-disulfonic acid (SITS). The CO2/HCO3 −-induced pHi increase was blocked when external Na+ was replaced with N-methyl-d-glucammonium (NMDG+). In the presence of HCO3 −, the Na+-driven HCO3 − transporter contributed to the pHi recovery from an acid load. For example, HCO3 − shifted the plot of acid-extrusion rate vs. pHi by 0.15–0.3 pH units in the alkaline direction. Also, with Na-H exchange inhibited by amiloride, HCO3 − increased acid extrusion 3.8-fold (pHi 6.20). When astrocytes were acid loaded in amiloride, with Li+ as the major cation, HCO3 − failed to elicit a substantial increase in pHi. Thus, Li+ does not appear to substitute well for Na+ on the HCO3 − transporter. We conclude that an amiloride-sensitive Na-H exchanger and a Na+-driven HCO3 − transporter are the predominant acid extruders in astrocytes.
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DOI：
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发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
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DOI：
10.1172/jci112948
发表时间：
1987-04
期刊：
The Journal of clinical investigation
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M. Soleimani;S. M. Grassi;P. Aronson
DOI：
10.1016/s0021-9258(19)84448-4
发表时间：
1986-07
期刊：
The Journal of biological chemistry
影响因子：
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作者：
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DOI：
10.1152/ajprenal.1995.268.2.f193
发表时间：
1995
期刊：
The American journal of physiology.
影响因子：
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作者：
Chen,LK;Boron,WF
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DOI：
10.1152/ajprenal.1995.268.2.f179
发表时间：
1995
期刊：
The American journal of physiology.
影响因子：
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作者：
Chen,LK;Boron,WF
通讯作者：
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