Comparative Analysis of Spontaneous and Stimulus-Evoked Calcium Transients in Proliferating and Differentiating Human Midbrain-Derived Stem Cells

Figure 2

Spontaneous calcium transients in cytosol of differentiating stem cells are dependent on intracellular and extracellular calcium supply. Fura-2-loaded cells were measured for 20 min at room temperature. The pattern of calcium transients from five representative cells is shown (a). The fraction of cells with calcium transients (cytosolic calcium increase followed by decrease) was calculated in each experiment (b), as was the number of transients per cell (c). The cells were incubated in the presence or absence of extracellular calcium as indicated on the figure. Pretreatment with thapsigargin in the absence of calcium was used to deplete the intracellular calcium stores (third bars in the two histograms). Ryanodine was used to study the role of ryanodine receptors. The mean values and SEM from 6–15 independent experiments (b) and 40–378 cells (c) are shown. ∗ indicate significant difference from the control value. Consecutive recordings (still images) of Fluo-4-loaded cells with a 60 sec interval ((d); corresponding video available, see Supplemental Figure ).

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