Only recently has it been recognized that intracellular Ca 2 + is an important cellular mediator in pancreatic ducts. The aim of the present study was to characterize the Ca 2 + efflux pathway in ducts freshly prepared from rat pancreas. Lowering of extracellular Na + concentration resulted in a significant increase in intracellular Ca 2 + . This effect was fast, reversible, dependent on the extracellular Na + concentration and did not correlate with intracellular pH changes. It was abolished in Ca 2 + -free solutions, indicating that the outwardly directed Na + gradient was directly coupled to a flufenamate insensitive Ca 2 + influx. Removal and reintroduction of extracellular Na + induced transient hyperpolarization and depolarization of V m , respectively. Taken together, our data indicate that pancreatic ducts possess an electrogenic Na + -Ca 2 + exchanger, which under control conditions is responsible for transporting Ca 2 + out of resting duct cells.