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Evidence for a sodium/calcium exchanger and voltage‐dependent calcium channels in adipocytes
Author(s) -
Pershadsingh Harrihar A.,
Lee L.-Y.,
Snowdowne Kenneth W.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81169-x
Subject(s) - aequorin , extracellular , photoprotein , chemistry , calcium , biophysics , sodium calcium exchanger , sodium , diltiazem , antagonist , intracellular , biochemistry , biology , receptor , organic chemistry
The objective of these studies is to identify and characterize Ca 2+ ‐transport systems that may be of potential importance in the action of Ca 2+ ‐mobilizing hormones in the adipocyte. Using the Ca 2+ ‐sensitive photoprotein, aequorin, [Ca 2+ ] i was estimated to be 0.15 μM, assuming an intracellular [Mg 2+ ] of 1 mM. Substitution of Na + with choline + caused a transient increase in [Ca 2+ ] i which was inversely related to extracellular [Na + ], consistent with operation of a mediated Na + ‐Ca 2+ exchange system. The stoichiometry was 3Na + :Ca 2+ . Elevation of extracellular K + caused an increase in [Ca 2+ ] i that was blocked by the Ca 2+ channel antagonist, diltiazem, by omitting extracellular Ca 2+ , or by substituting Sr 2+ for Ca 2+ . These findings indicate the presence of an Na + ‐Ca 2+ exchanger and voltage‐sensitive Ca 2+ channels in adipocytes.