Figure 3.

AQP isoform specificity of three selected compounds. A–C, cell water permeability was measured in calcein-loaded recombinant CHO cell lines. The structurally similar compounds 9016645 (A) and Z433927330 (B) show reversed isoform specificity. DFP00173 (C) specifically inhibits AQP3 over the homologous AQP isoforms AQP7 and AQP9. 9016645: IC₅₀, ∼6 μm (mAQP3); IC₅₀, N.D. (mAQP7); IC₅₀, N.D. (mAQP9). Z433927330: IC₅₀, ∼0.2 μm (mAQP7); IC₅₀, ∼0.7 μm (mAQP3); IC₅₀, ∼1.1 μm (mAQP9). DFP00173: IC₅₀, ∼0.1 μm (mAQP3); IC₅₀, N.D. (mAQP7); IC₅₀, N.D. (mAQP9). The AQP isoform was identified as a significant source for variation in two-way ANOVA for all three substances at p < 0.0001; n = 3. D, cell proliferation and viability of CHO cells are not reduced after 48 h of incubation with AQP inhibitors compared with solvent (DMSO). 1, DFP00173; 2, Z433927330; 3, RF03176. Calcein retention was not affected at 2.5 μm. Exposure to 25 μm of either DFP00173 or Z433927330 resulted in increased fluorescence (p < 0.001; n = 4 for inhibitors and 8 for DMSO). Error bars indicate standard deviation. AU, arbitrary units.