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Biophys J. 1994 Jul;67(1):177-82.

Calcium channels activated by depletion of internal calcium stores in A431 cells.

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1
Department of Pharmacology, Mayo Foundation, Rochester, Minnesota 55905.

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.

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PMID:
7918985
PMCID:
PMC1225347
DOI:
10.1016/S0006-3495(94)80467-9
[Indexed for MEDLINE]
Free PMC Article

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