Abstract
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.
Article PDF
Avoid common mistakes on your manuscript.
References
Anderson MF, Gregory RJ, Thompson S, Souza DW, Paul S, Mulligan RC, Smith AE, Welsh MJ (1991) Demonstration that CFTR is a chloride channel by alterations of its anion selectivity. Science Wash DC 252: 202–205
Anderson MP, Sheppard DN, Berger HA, Welsh MJ (1992) Chloride channels in the apical membrane of normal and cystic fibrosis airway and intestinal epithelia. Am J Physiol 263: L-L14
Devor DC, Simasko SM, Duffey ME (1990) Carbachol induces oscillations of membrane potassium conductance in a colonic cell line, T84. Am J Physiol 258: C318-C326
Díaz M, Valverde MA, Higgins CF, Rucareanu C, Sepúlveda FV (1993) Volume-activated chloride channels in HeLa cells are blocked by verapamil and dideoxyforskolin. Pflügers Arch 422: 347–353
Kubitz R, Warth, R, Allert N, Kunzelmann K, Greger R (1992) Small-conductance chloride channels induced by cAMP, Ca2+, and hypotonicity in HT29 cells: ion selectivity, additivity and stilbene sensitivity. Pflügers Arch 421: 447–454
Tabcharani JA, Chang X-B, Riordan JR, Hanrahan JW (1992) The cystic fibrosis transmembrane conductance regulator chloride channel. Iodide block and permeation. Biophys J 62: 1–4
Valverde MA, Hardy SP, Mintenig GM, Sepúlveda FV, Hyde SC, Gill DR, Higgins, CF (1993) Tamoxifen is a high affinity inhibitor of the P-glycoprotein-associated, cell volume regulated chloride channel. Submitted.
Wagner JA, Cozens AL, Schulman H, Gruenert DC, Stryer L, Gardner P (1991) Activation of chloride channels in normal and cystic fibrosis airway epithelium by multifunctional calcium/calmodulin-dependent protein kinease. Nature Lond 349: 793–796
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Valverde, M.A., Mintenig, G.M. & Sepúlveda, F.V. Differential effects of tamoxifen and I− on three distinguishable chloride currents activated in T84 intestinal cells. Pflugers Arch. 425, 552–554 (1993). https://doi.org/10.1007/BF00374885
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00374885