Modeling Buffered Ca2+ Diffusion Near the Membrane Implications for Secretion in Neuroendocrine Cells
- Klingauf, Jürgen
- Neher, Erwin
DOIAbstract
Secretion of catecholamines from neuroendocrine cells is relatively slow and it is likely that redistribution and buffering of Ca2+ is a major factor for delaying the response after a stimulus. In fact, in a recent study (Chow, R. H., J. Klingauf, and E. Neher. 1994. Time course of Ca2+ concentration triggering exocytosis in neuroendocrine cells. Proc. Natl. Acad. Sci. U.S.A. 91:12765–12769) Chow et al. concluded that the concentration of free calcium ([Ca2+]i) at a release site peaks at <10μM during short-step depolarizations, and then decays to baseline over tens of milliseconds. To check whether such a time course is consistent with diffusion theory, we modeled buffered diffusion in the vicinity of a Ca2+ channel pore. Peak [Ca2+]i and t...
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