Fig. 3.

Antinociceptive effects of fentanyl in the absence of MCAM (filled circles) and at various times after 10 mg/kg MCAM administration. The dose range for fentanyl tests remained the same, regardless of latencies obtained. Ordinates: latency to remove tails from 50°C water, expressed as a percentage of control (mean ± 1 S.E.M.) and averaged across seven rats for the dose-effect curve determined 45 days after MCAM and across eight rats for all other dose-effect curves. Abscissae: vehicle (S) or fentanyl dose in milligrams per kilogram of body weight.