Large Conductance Ca2+-Activated K+ Channels in Human Meningioma Cells |
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Authors: | R. Kraft K. Benndorf S. Patt |
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Affiliation: | (1) Institute of Pathology (Neuropathology), Friedrich-Schiller University of Jena, Bachstr. 18, D-07740 Jena, Germany, DE;(2) Institute of Physiology II, Friedrich-Schiller University of Jena, Goethestr. 1, D-07743 Jena, Germany, DE |
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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. Received 18 June 1999/Revised: 18 January 2000 |
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Keywords: | : Meningioma — Human — Patch clamp — BKCa channels — Cytoskeleton |
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