Rate of the reaction of carbon dioxide with human red blood cells

Abstract

A CO 2 electrode was adapted for use in a continuous-flow rapid-reaction apparatus to measure the kinetics of the hydration-dehydration reactions of CO 2 . The dehydration constant of the reaction was found to be 80 sec –1 at 37 C. Red blood cell suspensions were mixed with bicarbonate solutions to alter suddenly the Pco 2 around the cells from 42 to 57, and from 3 to 37 mm Hg. The velocity constants for the hydration of CO 2 inside the cell were 236 and 772 sec –1 , respectively, as compared with the uncatalyzed rate of 0.11 sec –1 . These uninhibited rates are 0.16 and 0.54 the potential catalyzed rate in the cell, suggesting that some other process is rate limiting. In the presence of 0.25 g/liter acetazolamide, the velocity constants decreased to 28 and 65 sec –1 , respectively.