Purinergic Signalling (2010) 6:429–445 437 Fig. 5 Nucleotide-induced responses of OB and PVZ cells are differentially affected by omission of extracellular Ca2+. a Fura-2/ AM stained acute slice preparation of the anterior telencephalon (a1; image acquired at rest). The area of the OB is shaded in red, and the area of the PVZ is shaded in green. Pixel correlation maps of the same slice (see “Materials and methods” section for details) obtained upon application of 2MeSATP (100 μM; a2 standard bath solution; a3 application after 10 min in Ca2+-free bath solution; a4 application after returning to standard bath solution). b The corresponding 2MeSATP- induced mean [Ca2+]i transients (±SEM) of all clearly identifiable responsive cells of the OB [b1 red traces: in normal bath solution (before and after application of Ca2+-free bath solution); light red traces: after 10 min in Ca2+-free bath solution; n=82 cells] and of the into the OB (Fig. 7b, b2). No staining was observed with antibodies against P2X1, P2X2, P2Y2, and P2Y4 receptor subtypes (data not shown). Influence of the telencephalic purinergic system on the processing of olfactory information As a last point, we investigated the possibility of a direct purinergic modulation of odorant information processing in the OB network. These experiments were performed using a nose–brain preparation (see Fig. 8a), and amino acids as olfactory stimuli. The nose–brain preparation allows to stimulate the olfactory epithelium with odorants and to PVZ [b2 green traces: in normal bath solution (before and after application of Ca2+-free bath solution); light green traces: after 10 min in Ca2+-free bath solution; n=59 cells]. c Mean peak responses (±SEM), expressed as percent of control response to 2MeSATP (10 μM), of 161 OB cells and 182 PVZ cells (two slices of the anterior telencephalon) in control conditions (red and green columns, respectively) and after 10 min in Ca2+-free bath solution (light red and light green column, respectively). d Same representation as in C with 2MeSATP [100 μM; 205 OB cells and 105 PVZ cells (two slices of the anterior telencephalon)]. e Same representation as in C with ATP [50 μM; 161 OB cells and 182 PVZ cells (two slices of the anterior telencephalon)]. (*p<0.05 and **p<0.01; unpaired t test). Abbrevia- tions: MOB main olfactory bulb, lv lateral ventricle simultaneously monitor the odorant-induced responses in the OB. Continuous stimulation of the OB with purinergic agonists (2MeSATP or ATP) or the P2 receptor antagonist suramin did not disrupt the odorant-induced responses of OB cells. Figure 8b shows the mean (±SEM) intracellular amino acid- induced [Ca2+]i transients of all responsive OB cells (b1; upper row) and the amino acid-induced [Ca2+]i transient of a randomly chosen individual cell of the same slice (b1; lower row). The overall appearance of the responses did not notably change after OB perfusion with 2MeSATP (gray-shaded area). Similarly, also prolonged application of ATP or suramin did not notably change the mean (±SEM) amino acid-induced