A chloride channel in rat pancreatic acinar AR42J cells is sensitive to extracellular acidification and dependent on ROS.

Extracellular acidification, playing a promoting role in the process of acute pancreatitis, has been reported to activate Cl channels in several types of cells. However, whether extracellular acidification aggravates acute pancreatitis via activating Cl channels remains unclear. Here, we investigated the effects of extracellular acidification on Cl channels in rat pancreatic acinar AR42J cells using whole-cell patch-clamp recordings. We found that extracellular acidification induced a moderately outward-rectified Cl current, with a selectivity sequence of I > Br ≥ Cl > gluconate, while intracellular acidification failed to induce the currents. The acid-sensitive currents were inhibited by Cl channel blockers, 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt hydrate and 5-Nitro-2-(3-phenylpropylamino) benzoic acid. After ClC-3 was silenced by ClC-3 shRNA, the acid-sensitive Cl currents were attenuated significantly, indicating that ClC-3 plays a vital role in the induction of acid-sensitive Cl currents. Extracellular acid elevated the intracellular level of reactive oxygen species (ROS) significantly, prior to inducing Cl currents. When ROS production was scavenged, the acid-sensitive Cl currents were abolished. Whereas, the level of acid-induced ROS was unaffected with silence of ClC-3. Our findings above demonstrate that extracellular acidification induces a Cl current in pancreatic acinar cells via promoting ROS generation, implying an underlying mechanism that extracellular acidification might aggravate acute pancreatitis through Cl channels.