...) (at the time indicated by the arrows) using Ca2+-containing medium, Ca2+-free medium and Ca2+-free medium following incubation of cells with the intracellular Ca2+ chelating agent BAPTA-AM (25 μmol l–1). Data are means ± s.e.m. of 19–128 cells from 3–16 independent preparations in A and of 28–39 cells from 3–4...

... at time zero. Fig. 4. Oscillation of intracellular Ca2+ concentration ([Ca2+]i) in a region of the atrial myocardium. The [Ca2+]i was determined by measuring the brightness of all pixels (N=1200) in the region, and the mean brightness ± s.e.m. was obtained. Error bars were all smaller than the size...