Figure 1. Effects of intrathecal morphine (10 [micro sign]g), morphine (3 [micro sign]g) plus PD135158 (80 [micro sign]g), morphine (10 [micro sign]g) plus PD135158 (20 [micro sign]g), and saline on the thermal nociceptive threshold of the right paw in the sham injury rat study. The ordinate shows the paw withdrawal latency. The abscissa shows time in minutes after drug injection. Each line represents the mean +/- SD of determinations made in four rats.