Antagonist dose-response curves for the inhibition of the Ca2+response to 100 nM morphine, 10 nM etorphine, and 100 nM DAMGO
| Morphine | Etorphine | DAMGO | ||||
|---|---|---|---|---|---|---|
| 5 to 7 s | 20 to 22 s | 5 to 7 s | 20 to 22 s | 5 to 7 s | 20 to 22 s | |
| Naloxone, IC50(nM) co-injection | 86 ± 14 | 32 ± 11 | 240 ± 40 | 74 ± 182-a | 24 ± 5 | 11 ± 4 |
| ratio 2.9 ± 0.9 | ratio 3.3 ± 0.7 | ratio 2.6 ± 1.0 | ||||
| Naloxone, IC50 (nM) −30 min | 0.75 ± 0.05 | 1.1 ± 0.4 | 0.16 ± 0.04 | 1.1 ± 0.72-a | N.D. | N.D. |
| ratio 0.74 ± 0.09 | ratio 0.19 ± 0.112-d | |||||
| Diprenorphine, IC50 (nM) co-injection | >10 μM | 15 ± 4 | 65 ± 13 | 56 ± 12 | 900 ± 290 | 8.5 ± 2.42-c |
| ratio 1.2 ± 0.3 | ratio 107 ± 0.192-e | |||||
| Diprenorphine, IC50 (nM) −30 min | 0.48 ± 0.04 | 0.2 ± 0.06 | 0.3 ± 0.04 | 2.5 ± 1.82-b | N.D. | N.D. |
| ratio 2.6 ± 0.8 | ratio 0.15 ± 0.062-f | |||||
The antagonists naloxone and diprenorphine were added either together with (co-injection) or 30 min before the agonist (−30 min). The IC50 values (±S.D.) are provided for fluorescence measured at 5 to 7 s or 20 to 22 s after agonists injection (see Fig. 3for fluorescence response profiles). The data in this table are derived from one series of experiments with the same batch of cells (n = 4 per data point). At least one repeat experiment was done for all conditions (except for DAMGO), yielding similar results.
N.D., not done.
Analysis of variance with Bonferroni post-test: comparing 20 to 22 s versus 5 to 7 s;
↵2-a p < 0.05;
↵2-b p < 0.01;
↵2-c p < 0.001. Student'st test: comparing ratio 5 to 7 s/20 to 22 s under the same condition (in same row),
↵2-d versus morphine p< 0.05;
↵2-e versus etorphinep < 0.001;
↵2-f versus morphine p < 0.01.