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. Author manuscript; available in PMC: 2009 May 6.
Published in final edited form as: Circ Res. 2008 Sep 11;103(8):e105–e115. doi: 10.1161/CIRCRESAHA.107.183236

Figure 6.

Figure 6

Local Fluo-5N photobleaching in permeabilized myocytes. A, Left, Ca2+ sparks and corresponding blinks during the Fluo-5N bleaching protocol. Recordings were made from 2 different SR Ca2+ release sites (s1, black trace; s2, gray trace) along the same scan line during 0.7 mmol/L tetracaine application. Experimental data were fitted by a monoexponential function (blue lines). Right, Potential mechanism of Fluo-5N bleaching variability. Fluorescence in a well-connected SR release site (s1) decays slowly because of fast diffusion of dye (blue arrows) from adjacent regions of the SR. An isolated SR release site (s2) bleaches fast because of restricted diffusion of the dye. The degree of intra-SR connectivity was symbolized by the number of free SR connections and diameter of free SR. B, The relationship between Ca2+ spark duration and the rate of Fluo-5N bleaching after tetracaine application.