ADH Action on Whole-Cell Currents by Cytosolic Ca2+-dependent Pathways in Aldosterone-treated A6 Cells |
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Authors: | T Nakahari Y Marunaka |
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Institution: | (1) Laboratory for Cellular and Molecular Physiology, Division of Respiratory Research, The Hospital for Sick Children Research Institute, University of Toronto Faculty of Medicine, Toronto, Ontario, Canada M5G 1X8, CA |
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Abstract: | We studied the characteristics of the basal and antidiuretic hormone (arginine vasotocin, AVT)-activated whole cell currents
of an aldosterone-treated distal nephron cell line (A6) at two different cytosolic Ca2+ concentrations (Ca2+]
c
, 2 and 30 nm). A6 cells were cultured on a permeable support filter for 10 ∼ 14 days in media with supplemental aldosterone (1 μm). At 30 nm Ca2+]
c
, basal conductances mainly consisted of Cl− conductances, which were sensitive to 5-nitro-2-(3-phenylpropylamino)-benzoate. Reduction of Ca2+]
c
to 2 nm abolished the basal Cl− conductance. AVT evoked Cl− conductances at 2 as well as 30 nm Ca2+]
c
. In addition to Cl− conductances, AVT induced benzamil-insensitive nonselective cation (NSC) conductances. This action on NSC conductances was
observed at 30 nm Ca2+]
c
but not at 2 nm Ca2+]
c
. Thus, cytosolic Ca2+ regulates NSC and Cl− conductances in a distal nephron cell line (A6) in response to AVT. Keeping Ca2+]
c
at an adequate level seems likely to be an important requirement for AVT regulation of ion conductances in aldosterone-treated
A6 cells.
Received: 6 May 1996/Revised: 28 June 1996 |
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Keywords: | : Patch clamp — Ion channel — Amiloride — Benzamil — NPPB |
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