Regulation of an outwardly rectifying Cl- conductance in single proximal tubule cells isolated from frog kidney.

1. A previous study has identified a Cl- conductance (GCl) in single proximal tubule cells isolated from frog kidney, which was activated by a protein kinase C (PKC)-dependent mechanism. 2. The whole-cell patch clamp technique was employed to examine further the properties and regulation of GCl. 3. GCl showed outward rectification, outward conductance was significantly greater than the inward conductance (56.1 +/- 15.6 vs. 16.8 +/- 6.4 microS cm-2, respectively, n = 8). DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid) blocked GCl in a dose- and voltage-dependent manner. 4. Other anions permeated the conductance. The anion selectivity sequence, I- > Br- > Cl- > gluconate, followed Eisenman's sequence I. 5. GCl could be activated by ATP. This process was dependent on ATP hydrolysis and channel phosphorylation. 6. G-protein activation inhibited the ATP-dependent activation of GCl. 7. These data support the hypothesis that activation of GCl by an increase in cell volume is dependent on ATP hydrolysis and channel phosphorylation via PKC.