Out-of-equilibrium CO2/HCO3- solutions and their use in characterizing a new K/HCO3 cotransporter.
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.
Zhao
J
J
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Hogan
E M
EM
Bevensee
M O
MO
Boron
W F
WF
D000818:Animals; D001369:Axons / Q000378:metabolism; D001639:Bicarbonates / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D049832:Decapodiformes; D006863:Hydrogen-Ion Concentration; D012996:Solutions
D001639:Bicarbonates; D002352:Carrier Proteins; D012996:Solutions; D002245:Carbon Dioxide