Rabbit pancreatic acini express CFTR as a cAMP-activated chloride efflux pathway

Cystic fibrosis transmembrane conductance regulator (CFTR) is responsible for adenosine 3',5'-cyclic monophosphate (cAMP)-activated chloride transport in epithelial cells. Isolated rabbit pancreatic acini possess a cAMP-activated chloride efflux mechanism distinct from zymogen granule secretion. To determine whether CFTR is expressed in acini, we used polymerase chain reaction (PCR) to amplify a 480-base pair (bp) sequence from reverse-transcribed rabbit acinar RNA. The PCR product was consistent with a 480-bp band amplified in T84 cells, and its sequence was > 90% homologous to human CFTR. CFTR antibody M3A7 recognized a 180- and a 160-kDa protein from acinar membranes consistent with bands seen in Chinese hamster ovary (CHO) cells transfected with CFTR. To determine if CFTR was responsible for the cAMP-activated chloride efflux previously demonstrated in pancreatic acini, we incubated acinar cells for 20 h with 1.75 microM CFTR antisense or sense oligodeoxynucleotide. Chloride efflux, in response to 8-bromoadenosine 3',5'-cyclic monophosphate and phorbol ester but not to calcium ionophore, was selectively inhibited by CFTR antisense oligodeoxynucleotide. Antisense oligodeoxynucleotide did not inhibit acinar amylase secretion. These findings indicate that isolated pancreatic acini can be used for future studies of CFTR expression and function.