Potassium Channels pp 267-277

Part of the Methods in Molecular Biology book series (MIMB, volume 491)

Rubidium Efflux as a Tool for the Pharmacological Characterisation of Compounds with BK Channel Opening Properties

  • Neil G. McKay
  • Robert W. Kirby
  • Kim Lawson


This chapter describes a method of assaying rubidium (Rb+) efflux as a measure of potassium channel activity. In this assay, rubidium acts as a tracer for potassium movement across the cell membrane. HEK 293 cells expressing the alpha subunit of the human brain large-conductance, voltage-activated, calcium-sensitive potassium channel (BK channel) are loaded with Rb+, washed, and then incubated under experimental conditions. The cell supernatant is removed, and the remaining cell monolayer lysed. These two samples contain Rb+ that has moved out of the cell and Rb+ that remains in the cell, respectively. Measurement of the Rb+ content of these samples by flame atomic absorption spectrometry allows calculation of the percentage Rb+ efflux and, depending on the experimental design, provides pharmacological data about the control and test compounds used. In this chapter, we describe the protocol and steps for optimisation and illustrate this with data obtained using NS1619, a well-characterised BK channel opener.

Key words

Potassium channels BK channel Rubidium efflux Atomic absorption spectrometry Channel openers Small molecules Drug discovery 


  1. 1.
    Bennett P. B. and Guthrie H. R. (2003) Trends in ion channel drug discovery: advances in screening technologies. Trends in Biotechnology 21, 563–569.CrossRefPubMedGoogle Scholar
  2. 2.
    Ebneth A. (2002) Ion channel screening technologies: will they revolutionise drug discovery? Drug Discovery Today 7, 227.CrossRefPubMedGoogle Scholar
  3. 3.
    Birch P. J., Dekker L. V., James I. F., Southan A., and Cronk D. (2004) Strategies to identify ion channel modulators: current and novel approaches to target neuropathic pain. Drug Discovery Today 9, 410–418.CrossRefPubMedGoogle Scholar
  4. 4.
    Zheng W., Spencer R. H., and Kiss L. (2004) High throughput assay technologies for ion channel drug discovery. Assay and Drug Development Technologies 2, 543–552.CrossRefPubMedGoogle Scholar
  5. 5.
    Gill S., Gill R., Lee S. S., Hesketh J. C., Fedida D., Rezazadeh S., Stankovich L., and Liang D. (2003) Flux assays in high throughput screening of ion channels in drug discovery. Assay and Drug Development Technologies 1, 709–717.CrossRefPubMedGoogle Scholar
  6. 6.
    Terstappen G. C. (1999) Functional analysis of native and recombinant ion channels using a high-capacity non-radioactive rubidium efflux assay. Analytical Biochemistry 272, 149–155.CrossRefPubMedGoogle Scholar
  7. 7.
    Apostoli P. (2002) Elements in environmental and occupational medicine. Journal of Chromatography B 778, 63–97.CrossRefGoogle Scholar
  8. 8.
    Hartness M. E., Brazier S. P., Peers C., Bate-son A. N., Ashford M. L. J., and Kemp P. J. (2003) Post-transcriptional control of human maxiK potassium channel activity and acute oxygen sensitivity by chronic hypoxia. Journal of Biological Chemistry 278, 51422–51432.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Neil G. McKay
    • 1
  • Robert W. Kirby
    • 1
  • Kim Lawson
    • 1
  1. 1.Biomedical Research Centre, Faculty of Health and WellbeingSheffield Hallam UniversitySheffieldUK

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