Figure 4

Fluorescence changes in neurons expressing YTnC and GCaMP6s indicators in dissociated culture in response to intracellularly induced APs. (a) Fluorescence changes in GECI-expressing cells to the train of 10 APs intracellularly induced with a frequency of 50 Hz. Ca²⁺ responses were averaged across representative recorded neurons from different wells (N = 6 and 7 neurons from 3 and 4 cultures for GCaMP6s and YTnC, respectively). Example of intracellular recording (grey) was obtained from one representative cell. (b) Dependence of the amplitudes of responses induced by different numbers of APs in neurons expressing YTnC and GCaMP6s. The linear regression shown in the figure was calculated for the 2–50 AP subset for both YTnC (R² = 0.9959) and GCaMP6s (R² = 0.9981). Note that in the range of 2 to 50 APs, dependence is linear for both indicators, whereas the amplitude of response to 100 APs in GCaMP6s-expressing neurons lies well below the linear regression line. At the same time, the response of YTnC to 100APs is located directly on the 2–50 regression line, i.e., dependence remains linear even for responses to strong stimulation. Values are shown as the means ± SEM.