Selective inhibition of potassium-stimulated rat adrenal glomerulosa cells by ruthenium red

Biochem Pharmacol. 1999 Jan 15;57(2):209-18. doi: 10.1016/s0006-2952(98)00285-8.

Abstract

The effect of the cationic dye, ruthenium red (RR), on ionic fluxes, Ca2+ signal generation, and stimulation of aldosterone production was studied in isolated rat adrenal glomerulosa cells. In these cells, increased extracellular [K+] as well as angiotensin II (Ang II) elevate cytoplasmic Ca2+ concentration and thereupon activate steroidogenesis. However, the mode of action of the two stimuli are different: while a dihidropyridine-sensitive mechanism contributes to the response to both agonists, Ang II induces Ca2+ release from intracellular stores and causes capacitative Ca2+ influx, whereas K+ was recently shown to activate a plasma membrane Ca2+ current (Igl) independently of membrane depolarization. The difference is reflected in the sensitivity of the response of the cells to RR. The Ang II-induced Ca2+ signal and aldosterone production were not inhibited, but rather slightly potentiated by the dye. This potentiation was probably the consequence of the membrane-depolarizing effect of RR, due to the observed inhibition of the resting K+ conductance. Conversely, Ca2+ signal and aldosterone production were significantly reduced by RR when the cells were stimulated by moderately elevated [K+] (6-8 mM). Our patch clamp studies suggest that this effect was related to the inhibition of different voltage-dependent and -independent inward Ca2+ currents and indicates the functional importance of the latter in the signal transduction of the potassium-stimulated glomerulosa cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / pharmacology
  • Animals
  • Calcium Channels / drug effects
  • Coloring Agents
  • In Vitro Techniques
  • Membrane Potentials / drug effects
  • Patch-Clamp Techniques
  • Potassium / antagonists & inhibitors*
  • Potassium Channel Blockers
  • Rats
  • Rats, Wistar
  • Ruthenium Red / pharmacology*
  • Stimulation, Chemical
  • Zona Glomerulosa / cytology
  • Zona Glomerulosa / drug effects*

Substances

  • Calcium Channels
  • Coloring Agents
  • Potassium Channel Blockers
  • Ruthenium Red
  • Angiotensin II
  • Potassium