title: Potassium conductances and proliferation in conditionally immortalized renal glomerular mesangial cells from the H-2Kb-tsA58 transgenic mouse.
abstract: The effects of the temperature-sensitive, immortalizing Simian Virus 40 T antigen, tsA58, on whole-cell potassium conductances were assessed in renal glomerular mesangial cells from H-2Kb-tsA58 transgenic mice [1]. MTT cell viability assay data indicated that in permissive (33 degrees C, 50 U ml-1 gamma-interferon, IFN+) and non-permissive (37 degrees C, without gamma-interferon, IFN-) culture conditions the oncogene was active and inactive respectively. In IFN+ cells whole-cell currents were inhibited by 10 mM 4-aminopyridine, 1 mM ATP and glibenclamide (glyburide, IC50 = 0.4 microM) and stimulated by cromakalim (EC50 = 40 microM). Furthermore, increases in pipette free calcium activity stimulated the potassium conductance (EC50 = 0.5 microM). Apamin inhibited this conductance (IC50 = 9 nM). None of these effects were observed in IFN- cells. The potassium conductance in IFN- cells was activated by a hyposmotic shock and this was inhibited by Gd3. These data indicate that (1) conductances consistent with ATP-sensitive and small, calcium-activated potassium channels are found in IFN+ cells, (2) an osmotically-sensitive channel is found in IFN- cells and (3) channel expression is dependent upon the activation of tsA58.
authors.affiliation: Department of Pharmacology, University of Cambridge, UK.
authors.forename: R D
authors.initials: RD
authors.lastname: Barber
authors.forename: A S
authors.initials: AS
authors.lastname: Woolf
authors.forename: R M
authors.initials: RM
authors.lastname: Henderson
mesh_terms: D015761:4-Aminopyridine / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000737:chemistry; D002118:Calcium / Q000494:pharmacology; D002455:Cell Division; D002460:Cell Line; D002586:Cesium / Q000737:chemistry; D005682:Gadolinium; D005920:Glomerular Mesangium / Q000737:chemistry*; D005905:Glyburide / Q000494:pharmacology; D006183:H-2 Antigens / Q000235:genetics; D007371:Interferon-gamma; D051379:Mice; D008822:Mice, Transgenic; D009857:Oncogenes; D009994:Osmolar Concentration; D015221:Potassium Channels / Q000737:chemistry*
chemical_list: D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D015221:Potassium Channels; D002586:Cesium; D001464:Barium; D000266:Adenylyl Imidodiphosphate; D007371:Interferon-gamma; D000255:Adenosine Triphosphate; D005682:Gadolinium; D015761:4-Aminopyridine; C038958:gadolinium chloride; D005905:Glyburide; D002118:Calcium