A Model-Independent Algorithm to Derive Ca super(2+) Fluxes Underlying Local Cytosolic Ca super(2+) Transients

• Published in: Biophysical journal 2005-04, Vol.88 (4), p.2403-2421
• Main Authors: Ventura, A C, Bruno, L, Demuro, A, Parker, I, Dawson, S P
• Format: Article
• Language: English
• ISSN: 0006-3495
• DOI: 10.1529/biophysj.104.045260

Local intracellular Ca super(2+) signals result from Ca super(2+) flux into the cytosol through individual channels or clusters of channels. To gain a mechanistic understanding of these events we need to know the magnitude and spatial distribution of the underlying Ca super(2+) flux. However, this is difficult to infer from fluorescence Ca super(2+) images because the distribution of Ca super(2+)-bound dye is affected by poorly characterized processes including diffusion of Ca super(2+) ions, their binding to mobile and immobile buffers, and sequestration by Ca super(2+) pumps. Several methods have previously been proposed to derive Ca super(2+) flux from fluorescence images, but all require explicit knowledge or assumptions regarding these processes. We now present a novel algorithm that requires few assumptions and is largely model-independent. By testing the algorithm with both numerically generated image data and experimental images of sparklets resulting from Ca super(2+) flux through individual voltage-gated channels, we show that it satisfactorily reconstructs the magnitude and time course of the underlying Ca super(2+) currents.