Abrahamsen J, Norrie B, Andersen P K, Stokke D B, Nedergaard O A
Department of Pharmacology, Odense University, Denmark.
Acta Anaesthesiol Scand. 1990 Nov;34(8):616-8. doi: 10.1111/j.1399-6576.1990.tb03157.x.
Calculations of pH in modified Krebs solutions by inserting PCO2 and total-CO2 in the Henderson-Hasselbalch (H.-H.) equation are obvious as the equation originally served for this purpose. An exact calculation of the relation between pH and PCO2 is complicated as the concentration of bicarbonate, the dissociation constant and the solubility of CO2 change. Furthermore, the dissociation constant in the H.-H. equation is constant only if activities are used in the equation instead of stoichiometric concentrations. We therefore investigated the influence of different carbon dioxide tensions and bicarbonate concentrations on directly measured pH of organ baths aerated with mass-spectrometric analyzed O2-CO2 gases. For reference precision buffers were used. The measured pH values differed distinctly from calculated pH values in the acidic and alkaline parts of the pH interval investigated (6.57-8.15). Measurements of actual pH with proper calibration standards therefore seem mandatory.
通过将二氧化碳分压（PCO₂）和总二氧化碳（total - CO₂）代入亨德森 - 哈塞尔巴尔赫（H.-H.）方程来计算改良克雷布斯溶液中的pH值是显而易见的，因为该方程最初就是用于此目的。由于碳酸氢盐浓度、解离常数和二氧化碳溶解度会发生变化，所以精确计算pH值与PCO₂之间的关系很复杂。此外，只有在方程中使用活度而非化学计量浓度时，H.-H.方程中的解离常数才是恒定的。因此，我们研究了不同二氧化碳张力和碳酸氢盐浓度对用质谱分析的O₂ - CO₂气体曝气的器官浴直接测量pH值的影响。使用参考精密缓冲液作为对照。在所研究的pH区间（6.57 - 8.15）的酸性和碱性部分，测量得到的pH值与计算得到的pH值明显不同。因此，使用适当的校准标准进行实际pH值的测量似乎是必不可少的。
