Different immunohistochemical localization for TMEM16A and CFTR in acinar and ductal cells of rat major salivary glands and exocrine pancreas

We investigated the mRNA expression and immunohistochemical localization of Cl channels, transmembrane member 16A (TMEM16A or anoctamin 1), and cystic fibrosis transmembrane conductance regulator (CFTR) in rat major salivary glands and exocrine pancreas. RT-PCR detected mRNA expression of TMEM16A and CFTR in the extracts of the parotid gland (PG), submandibular gland (SMG), sublingual gland (SLG), and pancreas. Immunoreactivity for TMEM16A was localized in the apical membrane of serous acinar and intercalated ductal cells in the PG and SMG as well as mucous acinar cells in the SLG; however, it was not detected in striated ductal cells of these tissues. Although striated ductal cells in the PG, SMG and SLG, and granular ductal cells in the SMG, were immunoreactive for CFTR in the luminal side, serous, mucous acinar, and intercalated ductal cells were not immunoreactive for CFTR in any of the major salivary glands. In the exocrine pancreas, immunoreactivity for TMEM16A was localized in the apical membrane of acinar cells, while immunoreactivity for CFTR was localized in the luminal side of intercalated ductal cells. These results suggest that different localization of TMEM16A and CFTR immunoreactivities reflects the respective functions of acinar and ductal cells in major salivary glands and exocrine pancreas.