title: Progesterone inhibits K conductance in plasma membrane of cultured renal epitheloid MDCK cells.
abstract: Progesterone causes natriuresis, an effect largely attributed to displacement of aldosterone from its receptor. The present study, however, demonstrates that progesterone (0.1, 1, and 10 mumol/1, respectively) also causes a rapid, fully reversible depolarization of Madin-Darby canine kidney (MDCK) cells (by 1.3 +/- 0.5, 4.1 +/- 0.7 and 12.3 +/- 1.5 mV, respectively). 17 alpha-Hydroxyprogesterone and dihydroxytestosterone are, by two orders of magnitude, less effective, whereas cholesterol, aldosterone, hydrocortisone, and estradiol (each up to 10 mumol/l) did not significantly alter the potential difference across the cell membrane. The effect of progesterone is blunted by antiprogestogen RU 486 (5 mumol/l). The progesterone-induced depolarization is paralleled by a decrease of potassium selectivity and an increase of cell membrane resistance and is abolished in the presence of the potassium channel blocker barium (10 mmol/l), as well as in the presence of 40 mmol/l potassium in the extracellular fluid. Neither removal of extracellular chloride or bicarbonate nor amiloride, ouabain, or pretreatment with pertussis toxin abolish the depolarizing effect of 5 mumol/l progesterone. In conclusion, acute administration of progesterone depolarizes MDCK cells by decreasing the potassium conductance of the cell membrane.
authors.affiliation: Institute for Physiology, University of Innsbruck, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Steidl
authors.forename: G
authors.initials: G
authors.lastname: Pinggera
authors.forename: M
authors.initials: M
authors.lastname: Ritter
authors.forename: F
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004848:Epithelium; D007668:Kidney; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011374:Progesterone / Q000494:pharmacology*
chemical_list: D015221:Potassium Channels; D011374:Progesterone