High active isoenzyme of carbonic anhydrase in rat calvaria osteoclasts. Immunohistochemical study.

Calvaria from newborn rats were used to localize carbonic anhydrase isoenzymes in bone tissue. Highly sensitive peroxidase-antiperoxidase method revealed strong reaction of high-active C form of carbonic anhydrase exclusively in the osteoclasts. There was no reaction in osteoblasts or fibroblasts but some population of bone marrow cells was positive. Isoenzyme B was found only in bone marrow cells. On the basis of the present and previous studies it is highly probable that carbonic anhydrase may have some crucial role in osteoclast mediated bone resorption. Carbonic anhydrase C may also be a suitable probe for studies of osteoclast function and origin.