Effect of carbonic anhydrase inhibition on mixed venous CO2 tension in anesthetized dogs

Abstract

The ventilation of one lung in dogs was isolated and that lung continually rebreathed into a small rubber bag. The Pco₂ of a sample of the gas in the rebreathing bag was compared with the Pco₂ calculated from pH and bicarbonate concentration determined in a sample of mixed venous blood drawn simultaneously. Before the injection of a carbonic anhydrase inhibitor, acetazolamide, the difference between the two values for Pco₂ was not significant. After acetazolamide, a highly significant difference (P < 0.001) was found. Apparently, when carbonic anhydrase was inhibited, the dissolved CO₂ of mixed venous blood did not attain equilibrium with bicarbonate by the time the blood entered the lung. Submitted on December 18, 1959