Related Experiment Video

Updated: Jun 27, 2026

Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors
09:57

Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors

Published on: February 4, 2016

Characterization of BK channel splice variants using membrane potential dyes

F Saleem1, I C M Rowe, M J Shipston

  • 1Centre for Integrative Physiology, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK.

British Journal of Pharmacology
|December 11, 2008
PubMed
Abstract

Insights

Large conductance calcium- and voltage-activated potassium (BK) channels have splice variants with differing sensitivities to calcium. The BK channel blocker paxilline effectively inhibits all variants, making it useful for functional assays.

Area of Science:

  • Molecular biology
  • Electrophysiology
  • Ion channel research

Background:

  • Large conductance calcium- and voltage-activated potassium (BK) channels are crucial for cellular excitability.
  • Extensive pre-mRNA splicing of the BK channel gene generates diverse functional variants.
  • Understanding splice variant-specific properties is key to their physiological roles.

Purpose of the Study:

  • To investigate the sensitivity of different BK channel splice variants to intracellular calcium.
  • To assess the inhibitory effects of paxilline on these splice variants.
  • To explore the utility of membrane potential assays for discriminating BK channel variants.

Main Methods:

  • Expression of murine BK channel splice variants (STREX, e22, ZERO) in HEK293 cells.
  • Utilized fluorescent membrane potential and patch clamp electrophysiology assays.
  • Analyzed responses to ionomycin-induced calcium influx.
  • Determined dose-dependent inhibition by paxilline.

Main Results:

  • Distinct BK channel splice variants (STREX, e22, ZERO) exhibited varying membrane hyperpolarization in response to calcium influx, with potency order STREX > e22 > ZERO.
  • The BK channel inhibitor paxilline showed similar potency (IC50 values) across all tested splice variants.
  • IC50 values for paxilline inhibition ranged from 0.35 to 0.70 µmol/L.

Conclusions:

  • Membrane potential assays effectively discriminate BK channel splice variants based on calcium sensitivity.
  • Paxilline is a potent inhibitor of BK channel splice variants with comparable IC50 values.
  • Paxilline can be reliably used in functional assays to inhibit BK channel activity regardless of the specific splice variant.

More Related Videos

FM Dye Cycling at the Synapse: Comparing High Potassium Depolarization, Electrical and Channelrhodopsin Stimulation08:31

FM Dye Cycling at the Synapse: Comparing High Potassium Depolarization, Electrical and Channelrhodopsin Stimulation

Published on: May 24, 2018

Subtype-specific Optical Action Potential Recordings in Human Induced Pluripotent Stem Cell-derived Ventricular Cardiomyocytes06:59

Subtype-specific Optical Action Potential Recordings in Human Induced Pluripotent Stem Cell-derived Ventricular Cardiomyocytes

Published on: September 27, 2018

Related Concept Videos

Potentiometry: Membrane Electrodes01:15

Potentiometry: Membrane Electrodes

Membrane electrodes, also known as p-ion electrodes, use membranes that selectively interact with free analyte ions, generating a potential difference across the membrane. The resulting membrane potential, known as the asymmetry potential, is not zero even when analyte concentrations on both sides of the membrane are equal. The membrane's response is typically not selective to a single analyte but proportional to the concentration of all ions in the sample solution capable of interacting at the...
The Resting Membrane Potential01:21

The Resting Membrane Potential

Overview
Resting Membrane Potential01:24

Resting Membrane Potential

The relative difference in electrical charge, or voltage, between the inside and the outside of a cell membrane, is called the membrane potential. It is generated by differences in permeability of the membrane to various ions and the concentrations of these ions across the membrane.
The Inside of a Neuron is More Negative
The membrane potential of a cell can be measured by inserting a microelectrode into a cell and comparing the charge to a reference electrode in the extracellular fluid. The...
Resting Membrane Potential01:24

Resting Membrane Potential

The relative difference in electrical charge, or voltage, between the inside and the outside of a cell membrane, is called the membrane potential. It is generated by differences in permeability of the membrane to various ions and the concentrations of these ions across the membrane.
The Inside of a Neuron is More Negative
The membrane potential of a cell can be measured by inserting a microelectrode into a cell and comparing the charge to a reference electrode in the extracellular fluid. The...
Patch Clamp01:18

Patch Clamp

Many fundamental cell functions such as muscle contraction and nerve transmission rely on the electrical signals produced by the movement of positively and negatively charged ions across the cell membrane. One competent method to record current flowing across the whole cell or single ion channel is the patch-clamp technique.
In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...