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BK channels in human glioma cells
1Department of Neurobiology, University of Alabama School of Medicine, Birmingham, Alabama 35294, USA.
Journal of Neurophysiology
|February 13, 2001
Summary
Human glioma cells express large-conductance, calcium-activated potassium (BK) channels. These ion channels are sensitive to intracellular calcium levels and may influence glioma cell behavior during migration and proliferation.
Area of Science:
- Neuroscience
- Cell Biology
- Biophysics
Background:
- Ion channels regulate essential cellular functions like proliferation and volume control in inexcitable cells.
- Glioma cells exhibit rapid proliferation and dynamic volume changes during invasive migration, suggesting a role for ion channels.
Purpose of the Study:
- To investigate the expression and function of ion channels in human glioma cell lines (D54MG and STTG-1).
- To characterize the properties of identified ion channels, particularly their voltage dependence, ion selectivity, and modulation by intracellular calcium.
Main Methods:
- Electrophysiological recordings (whole-cell and cell-attached patch) were used to measure ion currents.
- Ion channel activity was assessed under varying intracellular and extracellular ionic conditions and in response to specific pharmacological agents.
- Intracellular calcium concentrations were manipulated to study their effect on channel function.
Main Results:
- Human glioma cells exhibit voltage-dependent currents activating at positive voltages, with selectivity for K+ over other cations.
- These currents were significantly inhibited by known blockers of large-conductance, calcium-activated potassium (BK) channels.
- Elevated intracellular calcium levels shifted the voltage dependence of current activation to more negative potentials, consistent with BK channel activity.
- Single-channel recordings revealed large conductance (150-200 pS) channels with properties matching the whole-cell currents.
- Bradykinin stimulation activated TEA-sensitive currents, which were dependent on intracellular calcium.
Conclusions:
- Human glioma cells express functional large-conductance, calcium-activated potassium (BK) channels.
- These BK channels are modulated by intracellular calcium concentration and membrane potential.
- The identified BK channels likely play a significant role in regulating glioma cell volume, migration, and response to stimuli that alter intracellular calcium levels.