Figure 5. Receptor-mediated regulation of NaCl-induced expression of the AQP8 gene in RPE cells. The level of AQP8 mRNA was determined with real-time RT–PCR analysis in cells cultured for 6 h in iso- (control) and hyperosmotic (+ 100 mM NaCl) media (as indicated by the panels of the bars), and is expressed as folds of the unstimulated control. A: The following agents were tested: the inhibitor of the FGF receptor kinase, PD173074 (500 nM), the blocker of VEGF receptor-2, SU1498 (10 µM), the inhibitor of the PDGF receptor tyrosine kinase, AG1296 (10 µM), the blocker of the EGF receptor tyrosine kinase, AG1478 (600 nM), the inhibitor of TGF-β1 superfamily activin receptor-like kinase receptors, SB431542 (10 µM), the inhibitor of various G protein-coupled receptor subtypes, suramin (200 µM), the broad-spectrum matrix metalloproteinase inhibitor 1,10-phenanthroline (1,10-Phen; 10 µM), a recombinant human IL-1 receptor antagonist (IL-1RA; 1 µg/ml), and the NLRP3 inflammasome inhibitor‎ MCC950 (1 µM). B: Effect of exogenous IL-1β (10 ng/ml) on AQP8 gene expression. Vehicle control was made with dimethyl sulfoxide (DMSO; 1:500). Each bar represents mean ± standard error of the mean (SEM) obtained in three to ten independent experiments using cell lines from different donors. Significant difference vs. unstimulated control: *p<0.05. Significant difference vs. NaCl control: ^●p<0.05.