Aickin C C
J Physiol. 1984 Apr;349:571-85. doi: 10.1113/jphysiol.1984.sp015174.
A double-barrelled, pH-sensitive micro-electrode suitable for use in mammalian smooth muscle has been developed. It was shown to be unaffected by alteration of Na, K, Ca, Mg, Cl or CO2, and yielded the same results in mouse soleus muscle as had been obtained previously with the recessed-tip pH-sensitive glass electrode ( Aickin & Thomas, 1977 a). Intracellular pH (pHi) of the surface cells of guinea-pig vas deferens was 7.06 +/- 0.09 (n = 52, S.D. of an observation) in Krebs solution equilibrated with 3% CO2 at pH 7.35. The membrane potential (Em) was -65.5 +/- 6.7 mV. Thus pHi is about 0.8 units more alkaline than that predicted if H+ ions were passively distributed across the cell membrane. Alteration of extracellular pH (pHo) at constant CO2 caused a smaller change in pHi, by about 40% of that in pHo. The change was complete in 6-12 min and was of a similar magnitude whether the alteration was made in the continual presence or absence of CO2. Alteration of the CO2 level at constant pHo caused a rapid change in pHi followed by a slower, complete recovery. Thus the same stabilized pHi was recorded in different CO2-containing solutions. When CO2 was removed, the expected intracellular alkalinization was reduced or even obscured by a considerable acidification. pHi then stabilized at a mean value of 6.81 +/- 0.11 (n = 18) with an Em of -60.8 +/- 8.2 mV. The acidification expected on readmission of CO2 was minimized or obscured by a rapid recovery of pHi to the value previously recorded in CO2-containing solutions. A simultaneous increase in CO2 and decrease in pHo caused a rapid fall in pHi which increased in magnitude with decreasing pHo. This fall was followed by an incomplete recovery when pHo was above about 6.8 (but below 7.35), by no further change in pHi when pHo was about 6.7 and by a slow, continued fall in pHi when pHo was below 6.7. The intrinsic buffering power was calculated from the pHi changes observed on alteration of CO2. The values obtained increased in parallel with the extent to which pHi recovered following the imposed change, probably explained by an inseparable contribution to the minimization of the change by transport processes.(ABSTRACT TRUNCATED AT 400 WORDS)
已研发出一种适用于哺乳动物平滑肌的双管pH敏感微电极。结果表明，它不受钠、钾、钙、镁、氯或二氧化碳变化的影响，并且在小鼠比目鱼肌中得到的结果与之前使用凹尖pH敏感玻璃电极（艾金和托马斯，1977年a）所获得的结果相同。在与pH 7.35的3%二氧化碳平衡的 Krebs 溶液中，豚鼠输精管表面细胞的细胞内pH值（pHi）为7.06±0.09（n = 52，单次观察的标准差）。膜电位（Em）为-65.5±6.7 mV。因此，如果氢离子被动分布在细胞膜上，pHi比预测值约高0.8个单位。在恒定二氧化碳条件下改变细胞外pH值（pHo）会导致pHi的变化较小，约为pHo变化的40%。这种变化在6至12分钟内完成，无论在有无二氧化碳持续存在的情况下进行改变，其幅度相似。在恒定pHo条件下改变二氧化碳水平会导致pHi迅速变化，随后缓慢完全恢复。因此，在不同的含二氧化碳溶液中记录到相同稳定的pHi。当去除二氧化碳时，预期的细胞内碱化会因相当程度的酸化而降低甚至被掩盖。然后pHi稳定在平均值6.81±0.11（n = 18），Em为-60.8±8.2 mV。重新引入二氧化碳时预期的酸化会因pHi迅速恢复到之前在含二氧化碳溶液中记录的值而最小化或被掩盖。同时增加二氧化碳和降低pHo会导致pHi迅速下降，其幅度随pHo降低而增大。当pHo高于约6.8（但低于7.35）时，这种下降之后是不完全恢复；当pHo约为6.7时，pHi不再进一步变化；当pHo低于6.7时，pHi缓慢持续下降。根据在改变二氧化碳时观察到的pHi变化计算内在缓冲能力。获得的值与施加变化后pHi恢复的程度平行增加，这可能是由于转运过程对变化最小化的不可分割贡献所致。（摘要截选至400字）
