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.
Robson
L
L
Department of Physiology, Medical School, Leeds University, UK. l.robson@sheffield.ac.uk
Hunter
M
M
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D019204:GTP-Binding Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D011896:Rana temporaria
D018118:Chloride Channels; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid