Fig. 2.
Coexistence and characteristics of Na+ and Ca2+ waves. (A) Simultaneous Na+ and Ca2+ imaging showed that a Ca2+ wave is evoked by electrical stimulation and parallels the observed Na+ wave. (Upper) Intensity-modulated display image series of SBFI ratio (Na+ wave). (Lower) Fluorescence image series of Fluo-4 recorded simultaneously (Ca2+ wave). An initial reference image was subtracted from this image series to represent only the Ca2+ elevation over time after stimulation. (Scale bar, 200 μm.) (B) Fluo-4 fluorescence and SBFI ratio were plotted against time for four selected cells (circles in A Upper Right). (D) The speed of the Na+ wave was 40% slower than that of the Ca2+ wave. Data are means ± SEM (*, P < 0.05; n = 9 experiments).