Ca2+ transients evoked by consecutive ATP puffs applied onto the surface of the NAc slice. A: Time series of Ca2+ transients in response of the 1st (left, red) and the 2nd (middle, green) ATP-puff applied by pressure-ejection of 100 μM ATP through a 5-10 μM diameter patch-pipette for 60 s (long puff). Time refers to the time elapsed from the beginning of the ATP applications. Overlaying Ca2+ transients (right, yellow) suggest similarity of Ca2+ dynamics of consecutive ATP puffs. Scale bar is 50 μm. B: Comparison of Ca2+ signalling after the 1st and 2nd ATP application in the corpus callosum (N = 4), caudate putamen (N = 18) and NAc (N = 32). Data represent means ± S.E.M. (Mann-Whitney with Bonferroni post hoc test: *p < 0.05. C: The protocol applied for testing effects of different drugs/conditions on ATP-stimulated Ca2+ elevations in slices from the NAc. The difference between the two recordings in the number of cells (ΔN) or maximal fluorescence intensity Δ(dF/F0)max was expressed as the percentage of the effects of the first (control) stimulus (100 μM ATP or 10 μM 2-Me-S-ADP) application.