Inhibitory non-genomic effects of progesterone on Na+ absorption in epithelial cells from Xenopus kidney (A6).
The effect of the steroid hormone progesterone on transepithelial sodium transport was measured in confluent monolayers of the A6-cell line from Xenopus kidney. Apical permeabilization with Amphotericin B enabled us to measure the Na+/K+-pump current, and current-fluctuation analysis was used to analyze changes in apical channel density and gating characteristics. Basolateral progesterone (22.2 microM) had a rapid inhibitory effect on the Na+/K+-pump current, and a corresponding decrease in Na+ channel density. The effect occurred within some minutes and took about 50 min to reach a new steady state, in which 45% of the macroscopic current (ISC) was inhibited. Progesterone also inhibits the hypo-osmotic stimulation of Na+ channels which occurs in untreated monolayers. Compared with the known effects of adrenal steroids, our results show a rapid inhibitory action of a steroid hormone on Na+ absorption. The time profile of the progesterone effect suggests, at least in the first minutes, a non-genomic action of progesterone.
Fronius
M
M
Institute of Animal Physiology, Justus-Liebig-University Giessen, Germany.
Rehn
M
M
Eckstein-Ludwig
U
U
Clauss
W
W
D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D016477:Artifacts; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D007668:Kidney / Q000166:cytology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009997:Osmotic Pressure; D011374:Progesterone / Q000494:pharmacology*; D012964:Sodium / Q000493:pharmacokinetics*; D015222:Sodium Channels / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014981:Xenopus
D053503:Epithelial Sodium Channels; D015222:Sodium Channels; C058206:6-chloro-3,5-diaminopyrazine-3-carboxamide; D011374:Progesterone; D000584:Amiloride; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase