The effect of carbonic anhydrase inhibitors on the anionic composition of sheep's parotid saliva. With an appendix on uncatalysed carbon dioxide‐water kinetics by P. T. McTigue.

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Abstract
The effects of the carbonic anhydrase inhibitors acetazolamide, ethoxzolamide and benzolamide on the ionic composition of parotid saliva were studied in anesthetized sheep with access to the parotid blood vessels. The inhibitors were infused directly into the arterial blood supply to the gland to give blood concentrations in the range 10-5-10-2 M. Mean anionic concentrations at basal flow rate before inhibitor infusion were: bicarbonate 98 mmol/l, phosphate 15 mmol/l and Cl- 26 mmol/m. In the presence of inhibitors, bicarbonate concentration fell by 11 mmol/ml and phosphate and Cl- concentrations rose. Secreto-motor nerve stimulation increased bicarbonate concentration by 13 mmol/l before infusion of inhibitors and the concentrations of the other anions fell. The bicarbonate rise was abolished by the inhibitors and the fall in phosphate concentration was balanced by a rise in Cl- concentration. Only a small component of the bicarbonate ion transfer system in the sheep parotid gland is sensitive to the inhibitors. The relationship of these findings to a new enzyme with carbonic anhydrase action isolated from the sheep''s parotid gland is discussed.