Figure 7. Graphs show saline control intrathecal infusion over 90 min (mean of 5 + SEM animals per bar) and reversal with intraperitoneal administered Naloxone (1 mg/kg/body weight) of the antinociceptive response (top: percentage of maximal possible effect: Thermal withdrawal) and supraspinal side effects (bottom: percentage of maximal possible effect: supraspinal index) in percentage of maximal possible effect after 90 min of infusion of remifentanil (3 micro gram/min) and alfentanil (2 micro gram/min). Each bar represents the mean and SEM of four animals.