Figure 2. (A) The concentration versus time curves (mean +/- SD) of immunoreactive prostaglandin E²(PGE²;[white circle]) and acetaminophen ([black square]) in spinal microdialysate before (1-h baseline collection) and after intraperitoneal administration of 100 mg/kg acetaminophen (n = 6). The arrow indicates the time of formalin injection (0.5 h after acetaminophen administration). For graphical presentation, the midpoints of sampling intervals are used. (B) Behavioral data (mean flinches/min +/- SD at 5-min intervals, [black diamond]) and immunoreactive PGE²concentrations (mean +/- SD, [white circle]) 1 h after formalin injection.