<p><b>A</b> - Columns of the histogram show the mean (and SEM) PBf (expressed as % of the control PBf) measured every min (one column = 1 min) in 10 preparations when the control aCSF(7.4) (white columns) superfusing the preparations was first replaced by aCSF(7.4) containing fluoxetine (10–25 µM) for 20 min to block the serotonin transporter SERT (grey columns) and thereafter by aCSF(7.1) containing the same amount of fluoxetine for 5 min (black columns). Note that pre-treatment with fluoxetine did not significantly increase the PBf but abolished the PBf increase under acidosis. <b>B</b> - PBf changes (expressed as % of control) every min (one column) but for 14 preparations superfused with control aCSF(7.4) (white columns), aCSF(7.4) containing serotonin, 5-HT (1–5 µM) for 20 min (grey columns) and thereafter aCSF(7.1) containing the same amount of 5-HT for 5 min (black columns). Note that pre-treatment with 5-HT significantly increased the PBf by about 50% and, similarly to fluoxetine treatment, abolished the PBf increase under acidosis.</p
