Figure 9.

Effects of fentanyl alone or of fentanyl/naltrexone mixtures on gastrointestinal transit and respiration. Left panel shows effects of saline (Sal) or increasing doses of fentanyl alone. Abscissa: dose fentanyl in mg/kg. Ordinate: % mean saline control value for GI transit or respiration. All points show mean ± SEM from 12 mice (6 male, 6 female). Filled points indicate significantly different from saline, p < 0.05. The effects of 0.32 and 1.0 mg/kg fentanyl on respiration were not significantly different from each other (N.S.). Center panel and right panel show effects of different fentanyl/naltrexone mixtures composed of 0.32 mg/kg fentanyl + a naltrexone dose determined by the proportion. *Asterisk indicates significantly different from saline (Sal), and ^carat indicates significantly different from 0.32 mg/kg fentanyl alone (0.32 Fent), p < 0.05. All bars show mean ± SEM from 12 mice (6 male, 6 female), and points show data from individual mice.