Retention of carbon dioxide in tissue following carbonic anhydrase inhibition in dogs.

To evaluate the retention of carbon dioxide in tissue during the reduction of carbonic anhydrase activity following the administration of 5, 10, 20, or 30 mg/kg of acetazolamide in dogs, we measured carbon dioxide pressure (PCO2) in arterial blood, mixed venous blood, alveoli, and tissue. Respiration was maintained at a constant level. In the control (noninjected) group, PCO2 in tissue did not change for 3 hours under controlled respiration. Following the injection of 5 to 30 mg/kg of acetazolamide, PCO2 increased in arterial blood, mixed venous blood, and tissue in a dose-related manner, and decreased in the alveoli. The (a-et)PCO2 widened to 21.9 +/- 1.0 mmHg from 0.6 +/- 1.0 mmHg, and the (t-v)PCO2 to 16.1 +/- 2.0 mmHg from 5.1 +/- 0.6 mmHg, in response to acetazolamide. It is suggested that carbon dioxide is retained in tissue when carbonic anhydrase activity is inhibited by acetazolamide.