Activation of human IK and SK Ca2+ -activated K+ channels by NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime)

Biochim Biophys Acta. 2004 Oct 11;1665(1-2):1-5. doi: 10.1016/j.bbamem.2004.07.006.


We have identified and characterized the compound NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime) as a potent activator of human Ca2+ -activated K+ channels of SK and IK types, whereas it is devoid of effect on BK type channels. IK- and SK-channels have previously been reported to be activated by the benzimidazolinone, 1-EBIO and more potently by its dichloronated-analogue, DC-EBIO. NS309 is at least 1000 times more potent than 1-EBIO and at least 30 times more potent than DC-EBIO when the compounds are compared on the same cell.

Publication types

  • Comparative Study

MeSH terms

  • Benzimidazoles / pharmacology
  • Calcium Channel Agonists / pharmacology
  • Cell Line
  • Dose-Response Relationship, Drug
  • Humans
  • Indoles / pharmacology*
  • Intermediate-Conductance Calcium-Activated Potassium Channels
  • Kinetics
  • Oximes / pharmacology*
  • Patch-Clamp Techniques
  • Potassium Channels, Calcium-Activated / drug effects*
  • Potassium Channels, Calcium-Activated / metabolism
  • Small-Conductance Calcium-Activated Potassium Channels


  • 6,7-dichloro-1H-indole-2,3-dione 3-oxime
  • Benzimidazoles
  • Calcium Channel Agonists
  • Indoles
  • Intermediate-Conductance Calcium-Activated Potassium Channels
  • KCNN4 protein, human
  • Oximes
  • Potassium Channels, Calcium-Activated
  • Small-Conductance Calcium-Activated Potassium Channels
  • benzimidazol-2-one
  • 1-ethyl-2-benzimidazolinone