ROLE OF PH-SENSITIVE ION CHANNELS IN REGULATION OF CELL-VOLUME IN OPOSSUM KIDNEY-CELLS

Applying the patch-clamp technique to cultured opossum kidney (OK) cel ls, we investigated effects of pH on the activation of Cl- channels in duced by a hyposmotic shock. The Cl- conductance of cell membranes was measured in 145 mM NMG-Cl solution with the whole-cell configuration. Under control conditions, the Cl- conductance was almost negligible. When the cell was exposed to a hyposmotic medium, the Cl- conductance was remarkably elevated. This conductance change was reversibly inhibi ted by Cl- channel inhibitors, such as DIDS. The activation of Cl- con ductance was abolished by lowering the pH of cell interior (pH(i)) fro m 7.3 to 7.0, but not influenced by changing the bath pH (pH(e)). We c onclude that the Cl- channel activation by a hyposmotic challenge is h ighly sensitive to pH(i).