Renaud J M, Allard Y, Mainwood G W
Can J Physiol Pharmacol. 1986 Jun;64(6):764-7. doi: 10.1139/y86-130.
The intracellular pH of frog sartorius muscles exposed to an extracellular pH 8.0 (25 mM HCO3-, 1% CO2) was 6.9-7.1. Following a fatiguing stimulation period (one tetanic contraction per second for 3 min), the intracellular pH was 6.5-6.7. When similar experiments were repeated with frog sartorius muscles exposed to pH 6.4 (2mM HCO3-, 1% CO2), the intracellular pH was 6.8-6.9 at rest and 6.3-6.4 following fatigue. So, in both experiments the intracellular pH decreased by 0.4-0.5 pH unit during fatigue. When the CO2 concentration of the bathing solution was increased from 1 to 30%, the intracellular pH of resting muscles decreased from 7.0 to 6.2-6.3. Although the effect of CO2 on the intracellular pH was greater than the fatigue effect, the decrease in tetanic force with CO2 was less than 40%, while during fatigue the tetanic force decreased by at least 70%. Therefore in frog sartorius muscle the decrease in tetanic force during fatigue exceeds the decrease that is expected from just a change in intracellular pH.
暴露于细胞外pH值为8.0（25 mM HCO₃⁻，1% CO₂）的青蛙缝匠肌的细胞内pH值为6.9 - 7.1。在一段疲劳刺激期（每秒一次强直收缩，持续3分钟）后，细胞内pH值为6.5 - 6.7。当用暴露于pH值为6.4（2 mM HCO₃⁻，1% CO₂）的青蛙缝匠肌重复类似实验时，静息时细胞内pH值为6.8 - 6.9，疲劳后为6.3 - 6.4。所以，在这两个实验中，疲劳期间细胞内pH值均下降了0.4 - 0.5个pH单位。当浴液中CO₂浓度从1%增加到30%时，静息肌肉的细胞内pH值从7.0降至6.2 - 6.3。尽管CO₂对细胞内pH值的影响大于疲劳的影响，但CO₂导致的强直收缩力下降小于40%，而在疲劳期间强直收缩力至少下降70%。因此，在青蛙缝匠肌中，疲劳期间强直收缩力的下降超过了仅由细胞内pH值变化所预期的下降。
