Fig. 1.
Characterization of whole cell ATP stimulated currents. Exposure to ATP stimulates both outward and inward currents in human Mz-Cha-1 biliary epithelial cells. Whole cell currents were measured during basal conditions and during exposure to ATP (50 μM) (methods). A: representative whole cell recording. Currents measured at −80 mV (●), representing ICl−, and at 0 mV (○), representing IK+, are shown. ATP exposure is indicated by the bar. A voltage-step protocol (test potentials between −100 mV and +100 mV in 20-mV increments) was obtained a★ (basal), b★ (maximal outward current response), and c★ (maximal inward current response) as indicated. The current-voltage (I-V) plot shown in B was generated from these protocols. B: I-V relationship of whole cell currents during basal (▿) and ATP-stimulated maximal outward current (●) and maximal inward current (○) conditions.