Differential modulation of chloride conductances by iodinated gallic and trans-ferulic acids.

In this report we demonstrate that iodogallic acid (IGA) and iodoferulic acid (IFA) do not acutely affect transepithelial cation transport, however, prolonged basolateral application of IFA induced a delayed decrease in open-circuit current associated with increased transepithelial resistance. IGA and IFA have differential effects on volume-regulated anion currents (VRAC) and on cAMP-induced anion currents. In L929 cells, while IFA did not affect VRAC, IGA had a reversible and slightly voltage-dependent inhibitory effect with apparent IC50 values of approximately 10 μM that decreased with higher membrane voltage depolarization. On the other hand, IGA failed to inhibit cAMP-activated currents in Caco-2 cells, while IFA (100 μM) had a small but statistically significant inhibitory effect that was fully reversible. IGA and IFA exhibit differential effects on anion conductances and may represent candidate pharmacological tools for studying chloride channels, although their selectivity profile requires further characterization.