Figure 4. Detection of calcium concentration by fluorescence in living cells. (A) Fluorescence and fluorescence/phase contrast merged micrographs of isolated hDF obtained from young, elderly and HGPS donors incubated with the cell-permeant Ca2+ indicator Fluo-4 AM (2 μM) and at 200× magnification. Scale bars: 100 μm. (B) Quantification of Mean and Max fluorescence intensity (A.U. ± SEM). Significant differences calculated according to the Student’s t-test (p<0.05) are indicated.