ADH action on whole-cell currents by cytosolic Ca2+-dependent pathways in aldosterone-treated A6 cells.
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 approximately 14 days in media with supplemental aldosterone (1 microM). At 30 nm [Ca2+]c, basal conductances mainly consisted of Cl- conductances, which were sensitive to 5-nitro-2-(3-phenyl-propylamino)-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.
Nakahari
T
T
Division of Respiratory Research, The Hospital for Sick Children Research Institute, University of Toronto Faculty of Medicine, Toronto, Ontario, Canada M5G 1X8.
Marunaka
Y
Y
D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D017136:Ion Transport / Q000187:drug effects; D007684:Kidney Tubules / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015398:Signal Transduction / Q000187:drug effects; D014668:Vasotocin / Q000494:pharmacology*
D000450:Aldosterone; D002118:Calcium; D014668:Vasotocin