Inhibition by cAMP of calcium-activated chloride currents in cultured Sertoli cells from immature testis.
We have characterized a Ca2+-dependent Cl- current (ClCa) in cultured Sertoli cells from immature rat testis by using the whole cell recording patch-clamp technique. Cells dialyzed with pipette solutions containing 3 mm adenoside-triphosphate (ATP) and 1 microM free Ca2+, exhibited outward currents which were inhibited by 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and anthracene-9-carboxylic acid (9-AC) but insensitive to tetraethylammonium (TEA). Dialysis of cells with pipette solutions containing less than 1 nm free Ca2+ strongly reduced the currents indicating that they were Ca2+ dependent. With cells dialyzed with Cs+ glutamate-rich pipette solutions containing 0.2 mm EGTA, 10 microM ionomycin induced outward currents having properties of Ca2+-activated Cl- currents. With ATP-free pipette solution, the magnitude of currents was not modified suggesting the direct control by Ca2+. By contrast, addition of 0.1 mm cAMP in the pipette solution or the superfusion of cells by a permeant analogue of cAMP strongly reduced the currents. These results may suggest that ClCa is inhibited by cAMP-dependent protein kinase. Finally, our results do not agree with the model of primary fluid secretion by exocrine cells, but are in agreement with a hyperpolarizing effect of cAMP in primary culture of Sertoli cells and the release of a low Cl- and bicarbonate-rich primary fluid by these cells.
Lalevée
N
N
Laboratoire de Physiologie des Régulations Cellulaires, UMR 6558, UFR Sciences, 40 Avenue du Recteur Pineau 86022-Poitiers-Cedex, France.
Joffre
M
M
D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology; D002712:Chlorides / Q000502:physiology*; D000242:Cyclic AMP / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects / Q000502:physiology; D008297:Male; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D012708:Sertoli Cells / Q000502:physiology*
D018118:Chloride Channels; D002712:Chlorides; D000255:Adenosine Triphosphate; D000242:Cyclic AMP