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