A rabbit model for fentanyl-induced chest wall rigidity and the effect of apomorphine was evaluated. Eleven New Zealand adult rabbits were anesthetized and mechanically ventilated. An esophageal balloon catheter was used to estimate pleural pressure (P(pl)). Chest wall compliance (C(cw)) at baseline was calculated during pentobarbital anesthesia. A loading dose of 0.1 mg kg(-1) of fentanyl followed by infusion of 0.01 mg kg(-1) min(-1) was started in all animals, and C(cw) reassessed. In the rabbits that developed decreased C(cw), apomorphine 0.4 mg kg(-1) followed by a 0.004 mg kg(-1) min(-1) was administered and C(cw) was reassessed. C(cw) at baseline and after fentanyl and fentanyl+apomorphine were compared with one-way ANOVA followed by Bonferroni-Holm test (P<0.05). In 5 rabbits, C(cw) decreased significantly after fentanyl administration and apomorphine was able to restore C(cw) to baseline values. Rabbits can be used as a model for fentanyl-induced chest wall rigidity. Results from this study support central dopaminergic pathways as being at least partially responsible for the opioid-induced chest wall rigidity.