Abstract
Depletion of intracellular calcium stores induces transmembrane Ca2+ influx. We studied Ca(2+)- and Ba(2+)-permeable ion channels in A431 cells after store depletion by dialysis of the cytosol with 10 mM BAPTA solution. Cell-attached patches of cells held at low (0.5 microM) external Ca2+ exhibited transient channel activity, lasting for 1-2 min. The channel had a slope conductance of 2 pS with 200 mM CaCl2 and 16 pS with 160 mM BaCl2 in the pipette. Channel activity quickly ran down in excised inside-out patches and was not restored by InsP3 and/or InsP4. Thapsigargin induced activation in cells kept in 1 mM external Ca2+ after BAPTA dialysis. These channels represent one Ca2+ entry pathway activated by depletion of internal calcium stores and are clearly distinct from previously identified calcium repletion currents.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Barium Compounds / pharmacology
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Benzoquinones / pharmacology
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Calcium / metabolism*
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Calcium Channels / drug effects
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Calcium Channels / physiology*
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Calcium Chloride / pharmacology
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Calcium-Transporting ATPases / antagonists & inhibitors
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Carcinoma, Squamous Cell
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Cell Adhesion
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Cell Line
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Chlorides / pharmacology
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Egtazic Acid / analogs & derivatives
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Egtazic Acid / pharmacology
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Electric Conductivity
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Humans
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Inositol Phosphates / pharmacology
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Ion Channel Gating / drug effects
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Kinetics
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Magnesium Chloride / pharmacology
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Membrane Potentials
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Terpenes / pharmacology
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Thapsigargin
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Time Factors
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Tumor Cells, Cultured
Substances
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Barium Compounds
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Benzoquinones
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Calcium Channels
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Chlorides
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Inositol Phosphates
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Terpenes
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Magnesium Chloride
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barium chloride
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2,5-di-tert-butylbenzoquinone
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Egtazic Acid
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Thapsigargin
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Calcium-Transporting ATPases
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1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
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Calcium Chloride
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Calcium