title: A model-independent algorithm to derive Ca2+ fluxes underlying local cytosolic Ca2+ transients.
abstract: 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.
authors.affiliation: Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Alejandra C
authors.initials: AC
authors.lastname: Ventura
authors.forename: Luciana
authors.initials: L
authors.lastname: Bruno
authors.forename: Angelo
authors.initials: A
authors.lastname: Demuro
authors.forename: Ian
authors.initials: I
authors.lastname: Parker
authors.forename: Silvina Ponce
authors.initials: SP
authors.lastname: Dawson
mesh_terms: D000465:Algorithms; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002021:Buffers; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling; D003600:Cytosol / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000494:pharmacology; D007477:Ions; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008962:Models, Theoretical; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D015203:Reproducibility of Results; D013997:Time Factors; D014981:Xenopus
chemical_list: D002021:Buffers; D015220:Calcium Channels; D005456:Fluorescent Dyes; D007477:Ions; D002118:Calcium