Hill E P, Power G G, Gilbert R D
J Appl Physiol Respir Environ Exerc Physiol. 1977 Jun;42(6):928-34. doi: 10.1152/jappl.1977.42.6.928.
The rate of pH decrease in dog blood after addition of CO2 (dissolved in saline) was measured in vitro with a combination pH electrode and fast-response amplifier. The pH change was found to have an apparent half time of 6.0 +/- 0.5 s at 38 degrees C, similar to that predicted by previous mathematical simulations on the basis of uncatalyzed CO2 hydration kinetics and the buffering characteristics of plasma. Measurements were also made in vivo in dogs by withdrawing blood rapidly from a carotid artery through a temperature-controlled chamber containing a pH electrode. When the flow was stopped, we measured the pH change which occurs in blood (after it leaves the lungs) as the slow dehydration of bicarbonate continues. The measured half time was 7.3 +/- 0.6 s, again agreeing well with predictions. Essentially the same half time was found when the direction of approach to chemical equilibrium was reversed by adding CO2 to the inspired air. The rate of the reactions could be increased markedly by hemolyzing the blood to release carbonic anhydrase into the plasma.
使用组合式pH电极和快速响应放大器在体外测量了向犬血中添加二氧化碳（溶解于盐水中）后pH值下降的速率。发现在38℃时，pH变化的表观半衰期为6.0±0.5秒，这与先前基于未催化的二氧化碳水合动力学和血浆缓冲特性进行的数学模拟预测结果相似。还通过一个装有pH电极的温度控制腔室，从犬的颈动脉快速抽血在体内进行了测量。当血流停止时，我们测量了血液（离开肺部后）中由于碳酸氢盐持续缓慢脱水而发生的pH变化。测得的半衰期为7.3±0.6秒，同样与预测结果吻合良好。当通过向吸入空气中添加二氧化碳使化学平衡的接近方向相反时，发现了基本相同的半衰期。通过使血液溶血以将碳酸酐酶释放到血浆中，反应速率可显著提高。
