RETENTION OF CARBON-DIOXIDE IN TISSUE FOLLOWING CARBONIC-ANHYDRASE INHIBITION IN DOGS

To evaluate the retention of carbon dioxide in tissue during the reduc tion of carbonic anhydrase activity following the administration of 5, 10, 20, or 30 mg/kg of acetazolamide in dogs, we measured carbon diox ide pressure (P(CO2)) in arterial blood, mixed venous blood, alveoli, and tissue. Respiration was maintained at a constant level. In the con trol (noninjected) group, P(CO2) in tissue did not change for 3 hours under controlled respiration. Following the injection of 5 to 30 mg/kg of acetazolamide, P(CO2) increased in arterial blood, mixed venous bl ood, and tissue in a dose-related manner, and decreased in the alveoli . The (a-et)P(CO2) widened to 21.9 +/- 1.0 mmHg from 0.6 +/- 1.0 mmHg, and the (t-vBAR)P(CO2) to 16.1 +/- 2.0 mmHg from 5.1 +/- 0.6 mmHg, in response to acetazolamide. It is suggested that carbon dioxide is ret ained in tissue when carbonic anhydrase activity is inhibited by aceta zolamide.