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Updated: Aug 12, 2026

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels
10:07

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels

Published on: January 27, 2013

Polymyxin B, a novel inhibitor of red cell Ca2+-activated K+ channel

L Varecka1, E Peterajová, J Pogády

  • 1Mental Health Research Center, Institute for Medical Bionics, Psychiatric Hospital, Czechoslovakia.

FEBS Letters
|December 10, 1987
PubMed

Insights

Polymyxin B (PXB) inhibits potassium (K+) efflux through the Ca2+-activated K+ channel in human red blood cells. This antibiotic targets the Gárdos effect, offering potential insights into ion channel modulation.

Area of Science:

  • Pharmacology
  • Ion Channel Physiology
  • Hematology

Background:

  • The Ca2+-activated K+ channel (Gárdos channel) plays a role in regulating red blood cell volume and ion homeostasis.
  • Polymyxin B (PXB) is a cyclic peptide antibiotic with known interactions with cell membranes.

Purpose of the Study:

  • To investigate the effect of Polymyxin B on the Ca2+-activated K+ channel (Gárdos effect) in human red blood cells.

Main Methods:

  • Experiments were conducted on intact human red blood cells.
  • The Gárdos effect was induced using various conditions, including Ca2+ with vanadate or propranolol, ATP depletion, and A23187 treatment.
  • Potassium efflux was measured to assess channel activity.

Main Results:

  • Polymyxin B (0.1-3.0 mg/ml) significantly inhibited K+ efflux mediated by the Gárdos effect.
  • Inhibition was observed across different experimental conditions designed to activate the Gárdos channel.
  • PXB did not inhibit the anion channel or Ca2+ entry, indicating specific action on the Ca2+-activated K+ channel.

Conclusions:

  • Polymyxin B directly inhibits the Ca2+-activated K+ channel in human red blood cells.
  • The precise mechanism of this inhibition requires further investigation.

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