Immunohistochemical Distribution of Carbonic Anhydrase in Rat Exorbital Lacrimal Gland

Ahn, Min; Lee, Song Eun; Nam, Kwang Il; Jung, Chaeyong; Lee, Seung won; Ahn, Kyu Youn; Bae, Choon Sang; Kim, Baik Yoon; Park, Sung Sik

Abstract

There are several carbonic anhydrase (CA) isozymes, which differ in their kinetic properties, tissue distribution, and subcellular localization. In this study, the distribution of CA isozymes I, II, IV, and IX was investigated in the rat exorbital lacrimal gland using Western blotting analysis and immunohistochemical staining. In the Western blotting analysis of the rat lacrimal gland, CA II and CA IX were expressed abundantly and CA IV was expressed weakly. Hematoxylin-eosin staining of the exorbital lacrimal gland showed a multilobular tubuloacinar gland composed of acinar and ductal cells. Immunohistochemical reaction revealed no CAI staining in acinar cells and positive staining in intercalated and small duct cells. CA II reactivity was detected in the supranuclear cytoplasm of acinar cells and appeared to vary between acini. The intercalated and collecting duct cells showed weak or no immunoreactivity for CA II. CA IV was detected in the intercalated and collecting duct cells but not at the acinar cells. CA IX was detected in the intercalated and collecting duct cells, and in only a few acinar cells. These results demonstrate the differential distribution of CA isoenzymes in the exorbital lacrimal gland of the rat and suggest that CA II is related mainly to the electrolyte metabolism of tears in the acinar cells and that CAs I, IV, and IX are related to the electrolyte metabolism of tears in the duct cells.