Abstract
Cellular Ca2+ buffers determine amplitude and diffusional spread of neuronal Ca2+ signals. Fixed Ca2+ buffers tend to retard the signal and to lower the apparent diffusion coefficient (D(app)) of Ca2+, whereas mobile buffers contribute to Ca2+ redistribution. To estimate the impact of the expression of specific Ca2+-binding proteins or the errors in Ca2+ measurement introduced by indicator dyes, the diffusion coefficient D(e) and the Ca2+-binding ratio κ(e) of endogenous Ca2+ buffers must be known. In this study, we obtain upper bounds to these quantities (D(e) < 16 μm2/s; κ(e) < 60) for axoplasm of metacerebral cells of Aplysia california. Due to these very low values, even minute concentrations of indicator dyes will interfere with the spatiotemporal pattern of Ca2+ signals and will conceal changes in the expression of specific Ca2+-binding proteins, which in the native neuron are expected to have significant effects on Ca2+ signals.
Original language | English |
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Pages (from-to) | 473-481 |
Number of pages | 9 |
Journal | Neuron |
Volume | 18 |
Issue number | 3 |
DOIs | |
State | Published - Mar 1997 |