Aims: K⁺ channels play a vital role in maintaining the membrane potential, which is a crucial component of the driving force for exocrine secretion. The molecular nature of K⁺ channels have been identified in pancreatic duct cells, however, their physiological function is unclear. We investigated functional K⁺ channels in native duct cells. Methods: Ducts were isolated from normal rat pancreas by collagenase digestion. We recorded single-channel and whole- cell currents using patch-clamp techniques, and performed immunohistochemical and reverse transcription polymerase chain reaction analyses. Results: We first confirmed that the ducts did not express a vascular endothelial marker platelet/endothelial cell adhesion molecule-1 (PECAM-1), but expressed cystic fibrosis transmembrane conductance regulator and cytokeratin 20, a marker of duct cells. In cell- attached single-channel recordings, we observed three types of K⁺ channels on basolateral membrane in unstimulated duct cells. The 38 pS channels are likely to mediate whole- cell inwardly rectifying K⁺ (Kir) currents. The properties of 90 pS and 170 pS channels are similar to those of Ca²⁺- activated K⁺ channels. We then identified Kir2.0 and SK4/IK1 (intermediate conductance Ca²⁺-activated K⁺ channel) subunits as molecular candidates of the channels. Conclusion: The present results suggest that these subunits may mediate native K⁺ currents responsible for setting the resting membrane potential and might be involved in secretion in pancreatic duct cells.