Immunohistochemical Localizaion of Carbonic Anhydrase Isozymes IV and IX in Rat Salivary Gland

Cho, Tae Young; Lee, Song Eun; Nam, Kwang Il; Jung, Chaeyong; Ahn, Kyu Youn; Bae, Choon Sang; Kim, Baik Yoon; Park, Sung Sik

Abstract

This study presents distribution of carbonic anhydrase (CA) isozymes IV and IX, membrane associated forms, and CA I and II, cytoplasmic forms, in rat parotid and submandibular glands using Western blot analysis and immunohistochemical staining. Western blot analysis demonstrated that CAs I, II and IX were found to be abundantly expressed, but CA IV was weakly expressed in parotid gland. Submandibular gland expressed abundant CAs I and II, weak CA IX, and undetectable level of CA IV. In hematoxylin-eosin staining, parotid gland was entirely composed of serous acini and their ducts while submandibular gland was mixed population of serous and mucous lobules. Most of lobules (submandibular gland proper type) contained mostly serous acini and their ducts with granular convoluted duct. Some lobules (sublingual gland type) contained mostly mucous acini with serous demilune and their ducts without granular convoluted duct. In parotid gland, CAs IV and IX were immunolocalized in duct cells and not in serous acinar cells. Immunoreactivity for CAs I and II was also detectable in duct cells. Serous acinar cells were positive for CA II, and negative for CA I. In submandibular gland, CAs IV and IX were immunolocalized in duct cells but not in acinar cells of both types of lobules. Immunoreactivity for CAs I and II was also detectable in duct cells of both types of lobules. Cells of serous acini and serous demilune were positive for CA II, and negative for CA I. Mucous cells were negative for both CAs I and II. These results demonstrate the distribution of CA isoenzymes in parotid and submandibular glands of the rat, and suggest CAs IV and IX as well as CAs I and II are related to electrolytes metabolism of saliva in duct cells.