Fig. 4. Time course of the transepithelial voltage normalized to the percentage of the control value (–19 mV), showing the effects of ouabain and concanamycin A. During the time period 1, ouabain (2.5 mmol l^-1) was present in the bath perfusate. During the time period 1+2, ouabain (2.5 mmol l^-1) and concanamycin A (10 µmol l^-1) were present in the bath perfusate. Infusion mode was used throughout the experiments shown. At the arrow, the preparation was withdrawn from the perfusion pipette.