Summary of astrocyte Ca2+ oscillation responses. Panel A, Frequency of Ca2+ oscillations in astrocytes under control conditions (open bars) and during a 2 min time window following application of 55 mM K+ (filled bars). Significant increases were observed in Snap25 wild type and heterozygous control cultures, in contrast to a decrease in the Snap25-/- cultures. Panel B, The mean amplitude of individual astrocyte Ca2+ oscillations was significantly increased following K+ application in control cultures. Each bar represents mean ± SEM from 5 different cultures. Only astrocytes that displayed spontaneous events prior to K+ were included in the analysis and responses from 3–5 cells per dish were averaged before calculating group means. (** P < 0.005; * P < 0.05).