Fig. 5.

Changes in paracellular permeability in control and polyamine-deficient IEC-6 cells with or without challenge with H₂O₂. A: basal levels of paracellular permeability. After cells were grown in control cultures or cultures containing DFMO or DFMO + SPD for 4 days, they then were trypsinized, plated at confluent density on the insert, and maintained under the same culture conditions for an additional 48 h. Membrane-impermeable tracer molecule, [¹⁴C]mannitol, was added to the insert medium, and the entire basal medium was collected 2 h thereafter for paracellular tracer flux assays. Values are means ± SE of data from 6 samples. *P < 0.05 compared with control cells and cells treated with DFMO + SPD. B: paracellular permeability in controls (a) and polyamine-deficient cells (b) after challenge with different concentrations of H₂O₂ for 3 h. After cells were treated with H₂O₂ for 1 h, [¹⁴C]mannitol was added to the insert medium, and levels of [¹⁴C]mannitol were measured 2 h thereafter. Values are means ± SE of data from 6 samples. *P < 0.05 compared with control cells.