Inhibition of carbonic anhydrase: its effect on carbon dioxide elimination by the lungs

The effect of carbonic anhydrase inhibition on carbon dioxide elimination by the lungs has been studied in dogs by the following four experimental approaches: 1) the alveolar pathway (PaOO2 and PaCOCO2) was measured during the hyperventilation which follows carbonic anhydrase inhibition and compared to the normal pathway at the same hyperventilation. 2) The alveolar gas tensions were measured following carbonic anhydrase inhibition when the ventilation was held constant. 3) The changes in PaCOCO2 were measured when the ventilation was suddenly, artificially changed to a new level in the presence of carbonic anhydrase inhibition and in normal animals. 4) The CO2 output was measured directly during the hyperventilation which results from carbonic anhydrase inhibition, during the same hyperventilation in the normal animal and following carbonic anhydrase inhibition when the ventilation is held constant. These experiments demonstrate an immediate fall in CO2 output relative to the ventilation when carbonic anhydrase is inhibited, resulting in CO2 retention until a new steady state has been reached. An hypothesis is presented to explain the effect of carbonic anhydrase inhibition on CO2 transport. Submitted on March 28, 1958