Fig. 3. Effects of PKA inhibitors on paracellular permeability. (A,B,D) Mock (open columns) and FLAG-tagged PCLN-1-expressing MDCK cells (closed columns) were treated with 50 µM H-89, 10 µM PKI or 50 µM DDA for 1 hour. When used, 100 µM 8-Br-cAMP (cAMP) was treated for 1 hour after the addition of DDA. TER, FITC-dextran-4k flux and Mg²⁺ transport from the apical to basal compartments were measured after treatment with each drug. ^*P<0.05 and ^**P<0.01, compared with control. ^##P<0.01, compared with DDA only. NS, not significant compared with the control. (C) Mg²⁺ transport from the apical to basal compartments was measured in mock (open circles) and FLAG-tagged PCLN-1-expressing MDCK cells (closed circles). After incubation at 37°C for 0.5, 1 or 2 hours, the basal compartment media were collected and subjected to Mg²⁺ measurement. ^**P<0.01, compared with mock cells.