A model-independent algorithm to derive Ca2+ fluxes underlying local cytosolic Ca2+ transients

ALEJANDRA C VENTURA; LUCIANA BRUNO; ANGELO DEMURO; IAN PARKER; SILVINA PONCE DAWSON

BIOPHYSICAL JOURNAL

The Biophysical Society

Año: 2005 vol. 88 p. 2403 - 2421

0006-3495

Local intracellular Ca(2+) signals result from Ca(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(2+) flux. However, this is difficult to infer from fluorescence Ca(2+) images because the distribution of Ca(2+)-bound dye is affected by poorly characterized processes including diffusion of Ca(2+) ions, their binding to mobile and immobile buffers, and sequestration by Ca(2+) pumps. Several methods have previously been proposed to derive Ca(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(2+) flux through individual voltage-gated channels, we show that it satisfactorily reconstructs the magnitude and time course of the underlying Ca(2+) currents.