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Journal Article

Secretory responses of rat peritoneal mast cells to high intracellular calcium.

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Penner,  R.
Department of Membrane Biophysics, MPI for biophysical chemistry, Max Planck Society;

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Neher,  E.
Department of Membrane Biophysics, MPI for biophysical chemistry, Max Planck Society;

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Citation

Penner, R., & Neher, E. (1988). Secretory responses of rat peritoneal mast cells to high intracellular calcium. FEBS Letters, 226(2), 307-313. doi:10.1016/0014-5793(88)81445-5.


Cite as: http://hdl.handle.net/11858/00-001M-0000-002D-EE3D-8
Abstract
The patch-clamp technique was used to investigate the secretory responses of rat peritoneal mast cells at various intracellular calcium concentrations ([Ca2+]i). When Calcium was introduced into the cell with pipette-loaded dibromo-BAPTA, elevation of [Ca2+]i into the range 1-10 microM induced membrane capacitance increases indicative of exocytosis in a concentration-dependent manner. At higher concentrations a decrease of the response was observed. Cells that were exposed to micromolar [Ca2+]i underwent morphological alterations resulting in swelling, which is indicative of cytoskeletal alterations. The presence of dibromo-BAPTA (4 mM) strongly inhibited secretion induced by GTP-gamma-S, thus hampering the contribution of G-protein-mediated stimulation. Application of the Ca2+ ionophore ionomycin resulted in transient increases in [Ca2+]i which were parallelled by Ca2+-dependent secretion. Effective buffering of the cytosolic calcium level below 1 microM abolished the secretory response. Our results show that an increase in [Ca2+]i can trigger secretion, but only if it is high and sustained. During physiological stimulation, however, secretion proceeds at [Ca2+]i below 1 microM. It is, therefore, concluded that mast cell degranulation under physiological conditions is not simply a result of an increase in [Ca2+]i, but that other second messenger systems in conjunction with calcium act synergistically in order to ensure fast and efficient secretion.