Zhao J, Hogan E M, Bevensee M O, Boron W F
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Nature. 1995 Apr 13;374(6523):636-9. doi: 10.1038/374636a0.
In typical physiological solutions, CO2 is in equilibrium with HCO3- and H+ (CO2 + H2O<==>HCO3- +H+). Because one cannot independently alter CO2 and HCO3- concentrations and pH, it is impossible to distinguish between the effects of CO2 and HCO3- on physiological processes. Here we describe a continuous-flow, rapid-mixing approach for generating out-of-equilibrium CO2/HCO3- solutions with a physiological pH and CO2 (but little HCO3-), or pH and HCO3- (but little CO2). We have exploited these out-of-equilibrium solutions to introduce HCO3- exclusively to either the outside or inside of a squid giant axon, and verify the presence of a new K/HCO3 cotransporter. The out-of-equilibrium approach could be useful in a variety of applications for independently controlling CO2 and HCO3- concentrations and pH.
在典型的生理溶液中，二氧化碳与碳酸氢根离子和氢离子处于平衡状态（二氧化碳 + 水⇌碳酸氢根离子 + 氢离子）。由于无法独立改变二氧化碳和碳酸氢根离子的浓度以及pH值，所以不可能区分二氧化碳和碳酸氢根离子对生理过程的影响。在此，我们描述了一种连续流动、快速混合的方法，用于生成具有生理pH值和二氧化碳（但碳酸氢根离子很少）或pH值和碳酸氢根离子（但二氧化碳很少）的非平衡态二氧化碳/碳酸氢根离子溶液。我们利用这些非平衡态溶液将碳酸氢根离子专门引入鱿鱼巨轴突的外部或内部，并验证了一种新的钾/碳酸氢根离子协同转运体的存在。这种非平衡态方法在各种独立控制二氧化碳和碳酸氢根离子浓度以及pH值的应用中可能会很有用。
