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

Abstract

A CO2 electrode was adapted for use in a continuous-flow rapid-reaction apparatus to measure the kinetics of the hydration-dehydration reactions of CO2. 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 Pco2 around the cells from 42 to 57, and from 3 to 37 mm Hg. The velocity constants for the hydration of CO2 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.