![Figure 2. Simultaneous determination of [Ca2+]c(t) and [Ca2+]SR(t) in a muscle cell. (A) Fluorescence of X-rhod-1 in cytosol. Cell perfused with EGTA solution subjected to the voltage clamp pulse drawn at top. Fluorescence was normalized to resting time average F0(x). The plot is of spatially averaged F(t)/F0. (B) R = F2(x,t)/F1(x,t) of simultaneously recorded line scans of fluorescence of the biosensor, D4cpv-Casq1 in this case, with specific wavelengths of excitation and emission given in Materials and methods. The plot is of spatially averaged R. The dashed line marks Rmin. (C) Plots of release flux (black) calculated from F(t)/F0 and [Ca2+]SR (red) calculated from R(t) by Eq. 1. The final [Ca2+]SR level reached during this depolarization is close to the average (namely 179 µM; listed in Table I). ID: 072309a_series106. Average of six line scans obtained with 3-min intervals at between 130 and 145 min after establishing whole-cell patch is shown.](https://cdn.rupress.org/rup/content_public/journal/jgp/138/2/10.1085_jgp.201010592/5/jgp_201010592_rgb_fig2.jpeg?Expires=1767799338&Signature=2ZKSrc7jPxlnHJbaPGfkCZpWKFjyooTqU-djLmbay~wMhk1xY1UcGJribfHP2sGo7NvHI4hAdAA07POzVlbeMyhmqnyM3W3Tcrw-xDJSVWVm6b4NHDQfb3oGBh2zIClSggDY1UEJHFI2QnEXKcZbsVXWQwK-EbbPEP7~qRxd~QQZt3nY-IL9wh-4bBMexyNArYgbAUQoO4xEGSKuEIb0358XMoOWmr0eV~YR2nz-6ZOOsAwXAkJKIuivjsLEhKHFUYFQX31tvXPLW0I~LazJ3OEAtJjODnZoPFx~Si1lqoDjOAC0~Hy39-NeY3RHyRd2LF0EYy~R2R-pXyqq-JsV2g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Simultaneous determination of [Ca2+]c(t) and [Ca2+]SR(t) in a muscle cell. (A) Fluorescence of X-rhod-1 in cytosol. Cell perfused with EGTA solution subjected to the voltage clamp pulse drawn at top. Fluorescence was normalized to resting time average F0(x). The plot is of spatially averaged F(t)/F0. (B) R = F2(x,t)/F1(x,t) of simultaneously recorded line scans of fluorescence of the biosensor, D4cpv-Casq1 in this case, with specific wavelengths of excitation and emission given in Materials and methods. The plot is of spatially averaged R. The dashed line marks Rmin. (C) Plots of release flux (black) calculated from F(t)/F0 and [Ca2+]SR (red) calculated from R(t) by Eq. 1. The final [Ca2+]SR level reached during this depolarization is close to the average (namely 179 µM; listed in Table I). ID: 072309a_series106. Average of six line scans obtained with 3-min intervals at between 130 and 145 min after establishing whole-cell patch is shown.
