Amplitude, full width at half maxima (FWHM) and area vary for individual spike in a multi-spike response.
The amplitude of calcium spike represents the maximum fold change in cytosolic calcium level. The area of calcium spike corresponds to the amount of calcium released in the cytoplasm and FWHM denotes the life span of the calcium spike in the cytoplasm. Panels (A), (B) and (C) show amplitude, FWHM and area for serotonin-induced calcium spikes (blue triangle), and ATP-induced distinct (red triangle) and overlapping (•) calcium spikes, respectively. The temporal profile of calcium response was intensity-normalized such that the maximum and minimum (basal) intensities corresponded to values 2 and 1, respectively, before fitting it with a multi-gaussian function. In case of serotonin and ATP-stimulated calcium spikes, R2 values for fitting of calcium spikes with Gaussian function ranged from 0.92–0.98 and 0.94–0.99, respectively. Values represent means ± SEM of more than 50 cells from at least four independent experiments. See Materials and Methods for more details.
