Effects of chloride channel inhibitors on H2O2-induced renal epithelial cell injury

Oxidative stress contributes to renal epithelial cell injury in certain settings. Chloride influx has also been proposed as an important component of acute renal epithelial cell injury. The present studies examined the role of Cl− in H2O2-induced injury to LLC-PK1 renal epithelial cells. Exposure of LLC-PK1 cells to 1 mM H2O2 resulted in the following: depletion of intracellular ATP content; DNA damage; lipid peroxidation; and a loss of membrane integrity to both small molecules, e.g., trypan blue, and macromolecules, e.g., lactate dehydrogenase (LDH), and cell death. Substitution of Cl− by isethionate or the inclusion of certain Cl− channel blockers, e.g., diphenylamine-2-carboxylate (DPC), 5-nitro-2-(3-phenylpropylamino)· benzoate (NPPB), and niflumic acid, prevented the H2O2-induced loss of membrane integrity to LDH. In addition, the H2O2-induced loss of membrane integrity was prevented by raising the osmolality of the extracellular solutions, by depletion of cell ATP, and by inhibitors of volume-sensitive Cl− channels. However, these maneuvers did not prevent the H2O2-induced permeability to small molecules or H2O2-induced ATP depletion, DNA damage, lipid peroxidation, or cell death. These results support the view that volume-sensitive Cl− channels play a role in the progressive loss of cell membrane integrity during injury.