| Autor: |
Kim, Thomas D., Eddlestone, Geoffrey T., Mahmoud, Sahar F., Kuchtey, John, Fewtrell, Clare |
| Zdroj: |
Journal of Biological Chemistry; December 1997, Vol. 272 Issue: 50 p31225-31229, 5p |
| Abstrakt: |
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. |
| Databáze: |
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