Table 2. Naloxone (3 μmol/L)-precipitated withdrawal responses of the guinea pig ileum incubated with different drugs at 37 °C for 4 h. Withdrawal responses %=withdrawl contracture/acetylcholine contracture×100%. n=10 guinea pigs. Mean±SEM. cP<0.01 vs vehicle; fP<0.01 vs codeine phosphate group. Vehicle: purified water. All other drugs were dissolved in purified water.
| Group | Dose/μmol·L−1 | Withdrawal responses/% |
|---|---|---|
| Vehicle | – | 4.7±4.6 |
| Codeine phosphate | 3 | 50.4±17.1c |
| Verticinone | 3 | 3.2±4.1f |
| Cholic acid | 3 | 5.6±3.5f |
| CA-Ver | 3 | 1.9±2.9f |