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

¹ Department of Physiology, Graduate School of Medicine, and Department of Anesthesiology, Schools of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

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.

Key Words: carbonic anhydrase • Diamox

Submitted on May 11, 1964

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