Figure 7. Mean lumen negative transepithelial voltages (V_te; - S.E.M.) of 4 anterior midguts stimulated with serotonin (0.2 μmol l⁻¹) in presence (grey bar) and absence (white bar) of luminal DIDS (1 mmol l⁻¹), and photographs of a representative preparation of the anterior midgut of larval (4^th instar) Aedes aegypti identical times after perfusion stop in presence (right) and absence (left) of luminal DIDS. Before V_te and alkalinization after the influence of DIDS were recorded, the tissues were exposed 10–30 minutes to the drug in the perfusate.