Differential effects of tamoxifen and I- on three distinguishable chloride currents activated in T84 intestinal cells.
The whole-cell mode of the patch-clamp technique has been used to monitor ionic currents in T84 colonic carcinoma cells. The cells were stimulated by either a cAMP cocktail, ionomycin or hypotonicity. Sizeable currents with distinct kinetics were observed after the stimulation with the different agonists. These kinetically distinct Cl- currents also presented a differential sensitivity to the anti-oestrogen Tamoxifen and to the halide I-. Tamoxifen only inhibits the volume activated Cl- current without affecting the other two. Substitution of extracellular Cl- by I- shifted the reversal potential towards more negative values both in the hypotonicity and ionomycin activated Cl- currents. The cAMP activated current responded to the Cl- substitution by I- with a blockade of both outward and inward currents, in addition to the displacement of the zero current level towards positive values. Thus, the use of these two simple tools, I- and tamoxifen, allows the distinction of Cl- channels in epithelial cells.
Valverde
M A
MA
Department of Cellular Physiology, AFRC Babraham Institute, Cambridge, UK.
Mintenig
G M
GM
Sepúlveda
F V
FV
D002277:Carcinoma / Q000473:pathology / Q000503:physiopathology*; D002712:Chlorides / Q000502:physiology*; D003110:Colonic Neoplasms / Q000473:pathology / Q000503:physiopathology*; D000242:Cyclic AMP / Q000494:pharmacology; D004553:Electric Conductivity; D007038:Hypotonic Solutions / Q000494:pharmacology; D007454:Iodides / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D002712:Chlorides; D007038:Hypotonic Solutions; D007454:Iodides; D013629:Tamoxifen; D015759:Ionomycin; D000242:Cyclic AMP