Pharmacological and Biophysical Properties of Swelling-Activated Chloride Channel in Mouse Cardiac Myocytes

The present study was designed to observe the properties of swelling-activated chloride channel (ICl.swell) in mouse cardiac myocytes using patch clamp techniques. In whole-cell recordings, hypotonic solution activated a chloride current that exhibited outward rectification, weak voltage-dependent inactivation, and anion selectivity with permeability sequence of I ‐ > Br ‐ > Cl ‐ . The current was sensitive to Cl ‐ channel blockers tamoxifen, NPPB and DIDS. In single-channel recordings, cell swelling activated a single channel current which showed outward rectification with open probability of 0.76 ±0.08 and conductance of 38.1±2.5 pS at +100 mV under [Cl ‐ ] symmetrical condition. I-V relation revealed the reversal potential as expected for a Cl ‐ -selective channel. These results suggested that in mouse cardiac myocytes, swelling-activated, outward rectifying chloride channel with a single channel conductance of 38.1±2.5 pS (at +100 mV under [Cl ‐ ] symmetrical condition) underlies the volume regulatory Cl ‐ channel.