Large Conductance Ca2+-Activated K+ Channels in Human Meningioma Cells

Large Conductance Ca2+-Activated K+ Channels in Human Meningioma Cells Cells from ten human meningiomas were electrophysiologically characterized in both living tissue slices and primary cultures. In whole cells, depolarization to voltages higher than +80 mV evoked a large K+ outward current, which could be blocked by iberiotoxin (100 nm) and TEA (half blocking concentration IC50= 5.3 mm). Raising the internal Ca2+ from 10 nm to 2 mm shifted the voltage of half-maximum activation (V 1/2) of the K+ current from +106 to +4 mV. Respective inside-out patch recordings showed a voltage- and Ca2+-activated (BK Ca ) K+ channel with a conductance of 296 pS (130 mm K+ at both sides of the patch). V 1/2 of single-channel currents was +6, −12, −46, and −68 mV in the presence of 1, 10, 100, and 1000 μm Ca2+, respectively, at the internal face of the patch. In cell-attached patches the open probability (P o ) of BK Ca channels was nearly zero at potentials below +80 mV, matching the activation threshold for whole-cell K+ currents with 10 nm Ca2+ in the pipette. Application of 20 μm cytochalasin D increased P o of BK Ca channels in cell-attached patches within minutes. These data suggest that the activation of BK Ca channels in meningioma cells does not only depend on voltage and internal Ca2+ but is also controlled by the cytoskeleton. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Large Conductance Ca2+-Activated K+ Channels in Human Meningioma Cells

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Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 2000 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002320001052
Publisher site
See Article on Publisher Site

Abstract

Cells from ten human meningiomas were electrophysiologically characterized in both living tissue slices and primary cultures. In whole cells, depolarization to voltages higher than +80 mV evoked a large K+ outward current, which could be blocked by iberiotoxin (100 nm) and TEA (half blocking concentration IC50= 5.3 mm). Raising the internal Ca2+ from 10 nm to 2 mm shifted the voltage of half-maximum activation (V 1/2) of the K+ current from +106 to +4 mV. Respective inside-out patch recordings showed a voltage- and Ca2+-activated (BK Ca ) K+ channel with a conductance of 296 pS (130 mm K+ at both sides of the patch). V 1/2 of single-channel currents was +6, −12, −46, and −68 mV in the presence of 1, 10, 100, and 1000 μm Ca2+, respectively, at the internal face of the patch. In cell-attached patches the open probability (P o ) of BK Ca channels was nearly zero at potentials below +80 mV, matching the activation threshold for whole-cell K+ currents with 10 nm Ca2+ in the pipette. Application of 20 μm cytochalasin D increased P o of BK Ca channels in cell-attached patches within minutes. These data suggest that the activation of BK Ca channels in meningioma cells does not only depend on voltage and internal Ca2+ but is also controlled by the cytoskeleton.

Journal

The Journal of Membrane BiologySpringer Journals

Published: May 1, 2000

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