Dendritic [Ca²⁺] dynamics in the presence of immobile buffers and of dyes

Abstract

We present a reaction-diffusion model of [Ca²⁺] regulation in neuronal dendrites, in the presence of high-affinity indicator and endogenous buffers. We investigate the applicability of equilibration assumptions for a slow, NMDAR-like source, present an analytical solution to the system in linear approximation, and discuss a possible scheme for extending this approximation’s applicability. We obtain data on spatial Ca²⁺ spread that suggest that dendritic Ca²⁺ signals of NMDAR origin can be localized to 2–3 μm with no need for differential buffering or spines. Finally, we show that the difficulties presented by dye saturation may be circumvented by using fluorescence tails as a probe of [Ca²⁺] peaks.