Fig. 2. Time course of the transepithelial voltage of the anterior stomach of a fourth-instar mosquito larva (Aedes aegypti) normalized to the percentage of the control value (–20 mV). During the time period indicated by the horizontal boxes (1), dinitrophenol (2.5 mmol l^-1) was present in the bath perfusate. Infusion mode was used throughout the experiment shown. At the arrow, the preparation was withdrawn from the perfusion pipette.