RESUMO
The distribution of carbonic anhydrase (CA) isoenzymes I, II, IV, and IX was investigated in pancreatic islet of the rat using Western blotting analysis and immunohistochemistry. Western blotting analysis demonstrated strong CAI and II expression, but weak CAIV and no CAIX expression. Immunohistochemical reaction of pancreatic islet revealed no staining for CAI and II. CAIV was detected in the peripheral cells of the islet. CAIX was detected in the peripheral cells and occasional in the centrally located cells. Signals for CAIV were observed at the plasma membrane and/or in the cytoplasm of islet cells. Location of CAIV in the A cells was confirmed by subjecting serial sections of pancreas to staining for CAIV and glucagon, which showed colocalization in the A cells. Immunohistochemical staining of pancreatic acinus revealed abundant staining for CAI in interacinar blood vessels and CAII in ductal and acinar cells. These results demonstrate the differential distribution of CA isoenzymes in pancreatic islet, and suggest that A cells of pancreatic islet might contain both CAIV and IX.