THE ROLE OF CARBONIC ANHYDRASE IN ANION SECRETION INTO CEREBROSPINAL FLUID

¹ Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville, Florida

The entry of total C¹⁴O₂ and Cl³⁶ from blood into cerebrospinal fluid (CSF) was studied in cats with ventriculo-cisternal perfusion both before and after the administration of acetazolamide, a carbonic anhydrase inhibitor. It was found that the normal animal accumulates total C¹⁴O₂, by hydration of CO₂ to HCO₃^-, at 5 times the rate of the inhibited animal, a difference that cannot be explained by changes in CSF production alone. The rate of entry of Cl³⁶ in the normal animal was about twice that found in the inhibited animal, a change that was the same as that in CSF formation rate. It thus appears that both HCO₃^- formation and C1^- transport into the CSF depend upon catalytic hydration of CO₂, a process which may be important in the physiologic regulation of CSF acid-base equilibria and fluid production.