A Model-Independent Algorithm to Derive Ca2+ Fluxes Underlying Local Cytosolic Ca2+ Transients

ALEJANDRA C. VENTURA, LUCIANA BRUNO, ANGELO DEMURO, IAN PARKER, AND SILVINA PONCE DAWSON.

BIOPHYSICAL JOURNAL

Lugar: Bethesda; Año: 2005 vol. 88 p. 2403 - 2421

0006-3495

Local intracellular Ca2+ signals result from Ca2+ flux into the cytosol through individual channels or clusters ofchannels. To gain a mechanistic understanding of these events we need to know the magnitude and spatial distribution of theunderlying Ca2+ flux. However, this is difficult to infer from fluorescence Ca2+ images because the distribution of Ca2+-bounddye is affected by poorly characterized processes including diffusion of Ca2+ ions, their binding to mobile and immobile buffers,and sequestration by Ca2+ pumps. Several methods have previously been proposed to derive Ca2+ flux from fluorescenceimages, but all require explicit knowledge or assumptions regarding these processes. We now present a novel algorithm thatrequires few assumptions and is largely model-independent. By testing the algorithm with both numerically generated imagedata and experimental images of sparklets resulting from Ca2+ flux through individual voltage-gated channels, we show that itsatisfactorily reconstructs the magnitude and time course of the underlying Ca2+ currents.