Fig. 5. FL accumulation in Malpighian tubules of Drosophila, and its inhibition by several potential substrates. N=3 tubules for each. PBD, 3-phenobenzoic acid (1 mmol l^–1); PAH, p-aminohippuyric acid (3 mmol l^–1); PBA, probenecid (0.5 mmol l^–1). ^*Change in uptake rate (second measurement period relative to first measurement period) in presence of inhibitor significantly different from uptake rate in absence of inhibitor; P<0.05, paired t-test.