Fig. 2. CP extracellular DA in response to the first and ninth 8 mg/kg AMPH run, compared with a single acute injection of 8 mg/kg AMPH. Dialysis samples were collected at 30 min intervals andBL (baseline) represents the median value of the three samples collected immediately before the first injection. AMPH or saline was administered every 2 hr (arrows). ThePeak Response for each injection, and the area under the curve (A.U.C.) for the 120 min interval after each injection are summarized in the graphs on theright. The response to the first injection of RUN 1 was significantly different from the ACUTEresponse (t > 2.21; # p < 0.05). The responses to later injections within each run were significantly different from the first injection of the same run (RUN 1 ANOVA: Peak Response,F = 9.73, p < 0.01,t > 2.95; A.U.C.,F = 9.50, p < 0.01,t > 2.25; RUN 9 ANOVA: Peak Response, F = 28.61, p< 0.01, t > 5.25; A.U.C.,F = 23.05, p < 0.01,t > 5.41) (* p < 0.05, **p < 0.01, *** p < 0.001). The responses during the ninth run were significantly different from the corresponding injections during the first run (t > 2.41; + p < 0.05, ++ p < 0.01).