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Ca 2+ ‐Atpase inhibitor, cyclopiazonic acid, releases Ca 2+ from intracellular stores in rbl‐2h3 mast cells and activates a Ca 2+ influx pathway that is permeable to sodium and manganese
Author(s) -
Falcone Daniel,
Fewtrell Clare
Publication year - 1995
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041640125
Subject(s) - cyclopiazonic acid , calcium , phorbol , chemistry , intracellular , biochemistry , egta , calcium in biology , mast cell , microbiology and biotechnology , biophysics , biology , protein kinase c , signal transduction , immunology , organic chemistry
Abstract Cyclopiazonic acid has been reported to inhibit the Ca 2+ ‐ATPase of intracellular calcium stores in some nonexcitable cell types, such as myeloid cells and lymphocytes. The present study examines the effects of cyclopizonic acid on rat basophilic leukemia (RBL) cells, a mucosal mast cell line. Addition of cyclopiazonic acid to fura‐2‐loaded RBL cells evoked a biphasic increase in free ionized intracellular calcium. Release of stored calcium accounted for the first phase of this response. The second phase was determined to be calcium entering through an influx pathway activated by cyclopiazonic acid. The influx pathway was selective for calcium, But was somewhat permeable to manganese. However, in a Ca 2+ ‐free solution containing EGTA, sodium ions permeated freely. This influx pathway appears to be identical to that which is activated by antigen, the physiological stimulus to the cells. Cyclopiazonic acid also induced secretion when combined with the phorbol ester 12‐0‐tetradecanoyl phorbol 13‐acetate, which activates protein kinae C. © 1995 Wiley‐Liss, Inc.