Inhibitory non-genomic effects of progesterone on Na+ absorption in epithelial cells from Xenopus kidney (A6)

J Comp Physiol B. 2001 Jun;171(5):377-86. doi: 10.1007/s003600100186.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amiloride / analogs & derivatives*
  • Amiloride / pharmacology
  • Animals
  • Artifacts
  • Biological Transport / drug effects
  • Biological Transport / physiology
  • Cell Line
  • Dose-Response Relationship, Drug
  • Electric Stimulation
  • Electrophysiology
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Epithelial Sodium Channels
  • Kidney / cytology*
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Osmotic Pressure
  • Progesterone / pharmacology*
  • Sodium / pharmacokinetics*
  • Sodium Channels / metabolism
  • Sodium-Potassium-Exchanging ATPase / metabolism
  • Xenopus

Substances

  • Epithelial Sodium Channels
  • Sodium Channels
  • 6-chloro-3,5-diaminopyrazine-3-carboxamide
  • Progesterone
  • Amiloride
  • Sodium
  • Sodium-Potassium-Exchanging ATPase