Inhibition of Bone Resorption by Acetazolamide in the Rat¹

Abstract

The carbonic anhydrase inhibitor, acetazolamide, has been found to elicit a hypocalcemic response in acutely nephrectomized rats. This effect cannot be attributed to changes in pCO2, pH citrate, phosphate or protein. Administration of acetazolamide to parathyroidectomized- nephrectomized rats has been shown to inhibit the hypercalcemic response to parathyroid extract and dibutyryl cyclic 3',5'- AMP. The hypercalcemic response to epinephrine was not inhibited in the same preparation. These data are consistent with the hypothesis that cyclic 3',5'-AMP is the second messenger of parathyroid hormone in its action on bone, and that carbonic acid production may be a later, or possibly the final, messenger of the hormone.(Endocrinology87: 1129, 1970)