Failure of parathyroid hormone and cyclic AMP to inhibit renal carbonic anhydrase.

It has been suggested that the parathyroid hormone and cyclic AMP produce their bicarbonaturic effects through inhibition of renal carbonic anhydrase. In the present study, the incubation of renal carbonic anhydrase with parathyroid hormone or cyclic AMP in presence of ATP, Mg++ and K+ ions, did not produce any inhibition of the enzyme when the pH of the solution was maintained above 7. It is concluded, that parathyroid hormone and cyclic AMP produce urinary bicarbonate excretion by a mechanism independent of carbonic anhydrase inhibition.