Inhibitory mechanisms of H+‐ATPase inhibitor bafilomycin A1 and carbonic anhydrase II inhibitor acetazolamide on experimental bone resorption

The effects of the vacuolar‐type H+‐ATPase inhibitor bafilomycin A1 (baf. A1) and the carbonic anhydrase II inhibitor acetazolamide (AZ) on bone resorption and procathepsin L secretion of rat osteoclasts were investigated using the bone slice assay method, pit formation test. Baf. A1 completely suppressed osteoclastic bone resorption stimulated by parathyroid hormone (PTH), but did not affect procathepsin L secretion, while AZ suppressed both bone resorption and procathepsin L secretion. These findings suggest that bone resorption by procathepsin L secretion and its processing are regulated by proton production and proton secretion.