Correlating Ca2+ responses and secretion in individual RBL-2H3 mucosal mast cells.

Kim TD, Eddlestone GT, Mahmoud SF, Kuchtey J, Fewtrell C
J Biol Chem. 1997 272 (50): 31225-9

PMID: 9395446 · DOI:10.1074/jbc.272.50.31225

The role of Ca2+ in stimulus-response coupling in nonexcitable cells is still not well understood. The Ca2+ responses of individual cells are extremely diverse, often displaying marked oscillations, and almost nothing is known about the specific features of these Ca2+ signals that are important for the functional response of a cell. Using the RBL-2H3 mucosal mast cell as a model, we have studied the temporal relationship between changes in intracellular Ca2+ and serotonin secretion at the single-cell level using simultaneous indo-1 photometry and constant potential amperometry. Secretion in response to antigen never occurs until intracellular Ca2+ is elevated, nor is it seen during the first few oscillations in Ca2+. Exocytotic events tend to be clustered around the peaks of oscillations, but excellent secretion is also seen in cells with sustained elevations in Ca2+. Ca2+ release from stores in the absence of influx fails to elicit secretion. If refilling and continued release of Ca2+ from stores is prevented with thapsigargin, Ca2+ influx can still trigger secretion, suggesting that store-associated microdomains of Ca2+ are not required for exocytosis. Our findings demonstrate the importance of an amplitude-encoded Ca2+ signal and Ca2+ influx for stimulus-secretion coupling in these nonexcitable cells.

MeSH Terms (10)

Animals Calcium Cell Line Exocytosis Mast Cells Models, Biological Mucous Membrane Rats Receptors, IgE Signal Transduction

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