Calculated ED50 values [nmol (± 95% S.E.M.)] for drug combinations administered intrathecally in SP assay in WT and DOR-KO mice
| Drug | WT | DOR-KO | ||||||
|---|---|---|---|---|---|---|---|---|
| Ratio | Experimental | Theoretical | Interaction | Ratio | Experimental | Theoretical | Interaction | |
| DeltII + Clonidine | 1:1 | 0.0010 (±0.0005) | 0.22 (±0.19) | Synergistic* | 1:1 | 0.20 (±0.23) | 0.25 (±0.20) | No interaction a |
| Morphine + Clonidine | 1:1 | 0.058 (±0.029) | 0.56 (±0.27) | Synergistic* | 10:1 | 0.085 (±0.050) | 0.85 (±0.49) | Synergistic* |
| DAMGO + Clonidine | 1:100 | 0.14 (±0.056) | 0.19 (±0.09) | Additive | 1:10 | 0.022 (±0.0084) | 0.044 (±0.022) | Additive |
↵a Because DeltII was ineffective in DOR-KO mice, we compared the ED50 value for DeltII + clonidine combination to the ED50 value of clonidine alone (Student’s t test, P > 0.05) instead of running an isobolographic analysis.
↵* Experimental ED50 value < theoretical ED50 value (Student’s t test P < 0.05).