Neuronal activity is not modified by ATP-responsive astroglial Ca2+ signalling in the NAc slice. A: Fluo-4/tetrapotassium (200 μM) (upper image, left; red arrow) or OGB-1/hexapotassium (50 μM) (lower image left; red arrow) salt filled neurons (B left or right images) were distinguished by the presence of the fast Na+ current in the NAc slice. They did not colocalize (A upper and lower images, right; gray arrows indicate the orientation of the long ATP puff) with the long ATP puff-induced Ca2+ transients in NAc astrocytes (white arrows). Representative gray and green (dF/F0)max traces in A show astroglial and neuronal (B) Ca2+ fluorescence, respectively. Scale bar is 50 μm. B: Higher magnification of Fluo-4/tetrapotassium (200 μM) (B left) or OGB-1/hexapotassium (50 μM) (right) filled neurons. Scale bar is 50 μm. C: Summary of the average values of characteristic properties of postsynaptic currents recorded from neurons in the NAc slice. Currents were recorded at -70 mV holding potential using K-Gluconate-based pipette solution. Peak amplitudes and frequencies of individual currents were averaged throughout 1-min intervals. Mann-Whitney test used for statistical evaluation of amplitude and frequency variations, neither of them was found to be significant (18 neurons, 10 slices, 10 rats; p > 0.05).