- Diphenylamine-2-carboxylic acid (DPC), Usually an inhibitor of Cl- and non-selective cation channels, inhibits Cl-/HCO3- exchange and opens Cl- and cation conductances in rabbit gallbladder epithelium. Cremaschi, D., Porta, C., Meyer, G., Sironi, C., Garavaglia, M. Pflugers Arch. (2001)