The Expression of Carbonic Anhydrase Isozymes in Human Intestine

Lee, Dong Jin; Nam, Kwang Il; Lee, Seung Won; Ahn, Kyu Youn; Bae, Choon Sang; Kim, Baik Yoon; Park, Sung Sik

Abstract

The distribution of carbonic anhydrase (CA) isozymes I, II, IV, and IX was investigated in the human duodenum and colon using Western blotting analysis and immunohistochemical staining. A Western blotting analysis revealed an abundant expression of CAI and IX in the duodenum and colon. The expression of CAII and IV was detected in mucosa of duodenum and colon. The degree of expression, however, showed regional difference. The expression of CAII was strong in the duodenum and colon, and that of CAIV was weak in the duodenum and colon. Immunohistochemical staining of duodenum revealed no staining for CAI. CAII was detected at the columnar cells of surface epithelium and secretory cells and ductal cells of Brunner's gland. CAIV was detected at the ductal cells of Brunner's gland. CAIX was detected at the cells of intestinal gland and rare cells of the Brunner's gland. Immunohistochemical staining of colon showed a positive reaction of CAI and II at the columnar and goblet cells of surface epithelium, and CAIV and IX at the columnar cells of surface epithelium. These results demonstrate the differential distribution of CA isozymes in duodenum and colon, and suggest that Brunner's gland may contribute the control of acid-base balance in the duodenal lumen by secreting bicarbonate ion catalyzed by CAII and IV.