直接测量水蛭中枢神经系统中已识别的神经胶质细胞和神经元内的pH值。

Direct measurement of intracellular pH in identified glial cells and neurones of the leech central nervous system.

作者信息

Schlue W R, Deitmer J W

出版信息

Can J Physiol Pharmacol. 1987 May;65(5):978-85. doi: 10.1139/y87-155.

Abstract

Neutral carrier pH-sensitive double-barrelled microelectrodes were used to investigate intracellular pH (pHi) in leech neuropile glial cells and in Retzius neurones. The mean pHi of the glial cells was 6.87 +/- 0.13 (+/- SD, n = 27) in HEPES-buffered saline (pHo 7.4) and 7.18 +/- 0.19 (n = 13) in solutions buffered with 2% CO2- 11 mM HCO3-. The distribution of H+ ions in both the glia and neurones was found not to be in electrochemical equilibrium. To investigate pHi regulation, the pHi was decreased by exposure to CO2 or by adding and then removing NH4Cl. Acidification by any method was followed by a recovery to normal pHi values within minutes. The pHi recovery from acidification in neuropile glial cells in HEPES-buffered saline and CO2-HCO3- buffered saline was, however, blocked by removing external Na. In HCO3(-)-free solutions the diuretic amiloride (2 mM) reduced the rate of pHi recovery. In the presence of HCO3-, the rate of acid efflux was stimulated; the stilbene 4-acetamido-4'-isothiocyanatostilbene-2,3'-disulfonic acid (SITS; 0.5 mM) slowed pHi recovery. In HEPES buffered and CO2-HCO3- buffered solutions pHi regulation in neurones was inhibited by removing external Na. In HCO3(-)-free solutions amiloride reduced the rate of pHi recovery considerably. In the presence of HCO3-, SITS or amiloride slowed but did not completely block pHi recovery. We conclude that leech glial cells and neurones have two mechanisms of pHi regulation, one being Na+-H+ exchange and the other Na+ and HCO3- dependent.

摘要

使用中性载体pH敏感双管微电极来研究水蛭神经纤维网神经胶质细胞和雷丘斯神经元内的细胞内pH值（pHi）。在HEPES缓冲盐溶液（pHo 7.4）中，神经胶质细胞的平均pHi为6.87±0.13（±标准差，n = 27），在2% CO₂ - 11 mM HCO₃⁻缓冲的溶液中为7.18±0.19（n = 13）。发现神经胶质细胞和神经元中H⁺离子的分布均未处于电化学平衡状态。为了研究pHi调节，通过暴露于CO₂或添加然后去除NH₄Cl使pHi降低。通过任何方法酸化后，几分钟内pHi会恢复到正常pHi值。然而，在HEPES缓冲盐溶液和CO₂ - HCO₃⁻缓冲盐溶液中，去除细胞外Na会阻止神经纤维网神经胶质细胞酸化后的pHi恢复。在无HCO₃⁻的溶液中，利尿药氨氯吡脒（2 mM）降低了pHi恢复速率。在存在HCO₃⁻的情况下，酸流出速率受到刺激；芪类化合物4 - 乙酰氨基 - 4'-异硫氰酸芪 - 2,3'-二磺酸（SITS；0.5 mM）减缓了pHi恢复。在HEPES缓冲和CO₂ - HCO₃⁻缓冲溶液中，去除细胞外Na会抑制神经元中的pHi调节。在无HCO₃⁻的溶液中，氨氯吡脒显著降低了pHi恢复速率。在存在HCO₃⁻的情况下，SITS或氨氯吡脒减缓但并未完全阻止pHi恢复。我们得出结论，水蛭神经胶质细胞和神经元具有两种pHi调节机制，一种是Na⁺ - H⁺交换，另一种是依赖Na⁺和HCO₃⁻的机制。