Table 2. The effect of GRK2 co-expression on the affinity of µ-opioid receptor ligands.
| Untransduced pKL±s.e.m (KL nM) | GRK2 moi 5 pKL±s.e.m (KL nM) | Untransduced pKH ±s.e.m (KH nM) | GRK2 moi 5 KH±s.e.m (KH nM) | |
| DAMGO | 6.23±0.10 (589) | 6.65±0.04A (224) | 9.16±0.10 (0.692) | 9.16±0.17 (0.692) |
| Pfizer comp 1 | 7.37±0.08 (42.7) | 7.66±0.06A (21.9) | 10.32±0.13 (0.0479) | 10.29±0.17 (0.0513) |
| Morphine | 6.69±0.20 (204) | 6.96±0.03 (110) | 9.05±0.10 (0.891) | 8.85±0.28 (1.41) |
| Oxycodone | 5.12±0.05 (7590) | 5.25±0.07A (5623) | 7.48±0.18 (33.1) | 7.54±0.20 (28.8) |
| Endomorphin 1 | 6.31±0.08 (490) | 6.65±0.06A (224) | 8.90±0.15 (1.26) | 8.91±0.22 (1.23) |
| Endomorphin 2 | 6.40±0.08 (398) | 6.71±0.07A (195) | 8.66±0.15 (2.19) | 8.58±0.20 (2.63) |
| Naloxone | 8.65±0.04 (2.24) | 8.64±0.06 (2.29) | 9.24±0.18 (0.575) | 9.09±0.12 (0.813) |
Affinity for the low affinity site (KL) values were determined in competition binding assays versus [3H]diprenorphine in the presence of sodium ions and GTP, as described in the experimental section. Values are mean±s.e.m of three independent experiments. Affinity for the high affinity site (KH) values were determined in competition binding assays versus [3H]DAMGO in the presence of sodium ions, as described in the experimental section. Values are mean±s.e.m of four independent experiments.
A
Values are significantly different from those determined in the absence of GRK2 (p<0.05, two-tailed t-test).