Figure 4. Mean lumen negative transepithelial voltage (V_te; - S.E.M.) of 5 anterior midguts stimulated with serotonin (0.2 μmol l⁻¹) in absence (white bar) and presence (black bar) of concanamycin (50 μmol 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 concanamycin (50 μmol l⁻¹). On the average the tissues were exposed for 60 minutes to concanamycin before V_te and alkalinization after the influence of the drug were recorded. Asterisk: Mean V_te significantly different from the control (P < 0.05).