Micro‐electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres.
Micro‐electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres.
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微电极测量小鼠比目鱼肌纤维细胞内pH值和缓冲能力。
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
R. Thomas
中科院分区：
文献类型：
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作者：
C. Aickin;R. Thomas
1.使用凹尖pH敏感微电极在体外测量了小鼠比目鱼肌表面纤维的细胞内pH值（pHi）。2.在5% CO2和pH 7 - 40条件下，平均pHi为7 - 07 +/-0 - 007（S.E.在37 ℃时为7 - 23 +/-0 - 01，在28 ℃时为7 - 23 +/-0 - 01。这两个值之间的差异与37至28摄氏度之间中性pH值的变化相同。3.在恒定的外部pH值的CO2水平的改变引起了一个双相变化的pHi与快速位移，然后由一个较慢的部分恢复。由于回收不完全，在不同的CO2水平下记录了不同的稳定pHi值，CO2越高，pHi越低。pHi的差异在37和28 ℃下都非常显著。4.在恒定的外部pH值的CO2水平的改变也改变了膜电位（Em），CO2的增加导致Em的增加。Em对CO2水平的依赖性在快缩肌趾长伸肌中比比目鱼肌小得多。5.通过改变林格氏液的碳酸氢盐或CO2水平来改变外部pH值，导致pHi的变化平均为外部pH值变化的38 - 7%。通过改变CO2比通过改变碳酸氢盐实现pHi的变化快约10倍，并且方向相同。6.应用外部NH3和NH +4引起的细胞内迅速碱化，然后由一个缓慢的酸化。在去除外部NH3和NH +4，有一个大的和快速的酸化，随后由一个相当快的恢复pH值。7.在恒定的外部pH和恒定的外部碳酸氢盐下改变CO2水平以及去除外部NH3和NH +4时发生的pHi变化的大小表明，非CO2缓冲能力为45 m-当量H+离子/pH单位/升，恒定CO2缓冲能力为58 m-当量H+离子/pH单位/升。缓冲能力显然不受温度在37至28摄氏度之间变化的影响。8.得出的结论是，H+离子不是被动地分布在肌肉细胞膜上，并且pH值受到H+、OH-或HCO-3离子的主动转运的密切控制。
1. The intracellular pH (pHi) of surface fibres of the mouse soleus muscle has been measured in vitro using recessed‐tip pH‐sensitive microelectrodes. 2. In 5% CO2 and pH 7‐40, the mean pHi was 7‐07 +/‐ 0‐007 (S.E. of mean) at 37 degrees C and 7‐23 +/‐ 0‐01 at 28 degrees C. The difference between these tow values is the same as the change in neutral pH between 37 and 28 degrees C. 3. Alteration of the CO2 level at constant external pH caused a biphasic change in pHi with a rapid displacement followed by a slower partial recovery. Because the recovery was incomplete, different stable pHi values were recorded at different CO2 levels, the higher the CO2 the lower the pHi. The differences in pHi were highly significant both at 37 and 28 degrees C. 4. Alteration of the CO2 level at constant external pH also changed the membrane potential (Em), an increase in CO2 leading to an increased Em. The dependence of Em on the CO2 level was much smaller in the fast‐twitch muscle, extensor digitorum longus, than in soleus. 5. Changing external pH, either by alteration of the bicarbonate or CO2 level of the Ringer solution, caused pHi to change by a mean 38‐7% of the external pH change. The change in pHi was accomplished about 10 times more rapidly, and in the same direction, by altering CO2 than by altering the bicarbonate. 6. Application of external NH3 and NH+4 caused a rapid intracellular alkalinization followed by a slower acidification. On removal of external NH3 and NH+4, there was a large and rapid acdification, followed by a fairly rapid recovery in pHi. 7. The size of the pHi changes occurring on alteration of the CO2 level at both constant external pH and constant external bicarbonate, and on removal of external NH3 and NH+4, suggests a non‐CO2 buffering power of 45m‐equiv H+ ions/pH unit per litre and a constant‐CO2 buffering power of 58 m‐equiv H+ ions/pH unit per litre. The buffering power was apparently unaffected by a change in temperature between 37 and 28 degrees C. 8. It was concluded that H+ ions are not passively distributed across the muscle cell membrane, and that the pHi is closely controlled by the active transport of H+, OH‐ or HCO‐3 ions.