Affinities, expressed as KH, KL, and Ki values, of selected adenosine receptor agonists and antagonists to A3 receptors in human neutrophils
| [3H]MRE 3008F20 binding ( KH, KL) | RH | [3H]MRE 3008F20 binding ( Ki) + GTP | |
|---|---|---|---|
| nM | % | nM | |
| Agonists | |||
| CI-IB-MECA | 0.90 ± 0.1 | 29 ± 4 | |
| 70 ± 8 | 85 ± 11 | ||
| IB-MECA | 1.5 ± 0.3 | 30 ± 6 | |
| 110 ± 13 | 103 ± 17 | ||
| HE-NECA | 12 ± 2 | 24 ± 3 | |
| 680 ± 75 | 750 ± 90 | ||
| NECA | 20 ± 2 | 29 ± 5 | |
| 1,500 ± 300 | 1,800 ± 220 | ||
| (R)-PIA | 42 ± 4 | 25 ± 5 | |
| 2,600 ± 270 | 2,300 ± 250 | ||
| (S)-PIA | 286 ± 32 | 20 ± 6 | |
| 22,000 ± 3,000 | 25,000 ± 2,800 | ||
| Antagonists ( Ki) | |||
| MRE 3055F20 | 0.68 ± 0.15 | 0.53 ± 0.18 | |
| MRE 3062F20 | 0.88 ± 0.27 | 0.93 ± 0.22 | |
| MRE 3048F20 | 0.96 ± 0.31 | 1.2 ± 0.3 | |
| MRE 3046F20 | 1.3 ± 0.3 | 1.5 ± 0.4 | |
| MRE 3008F20 | 2.2 ± 0.2 | 2.0 ± 0.3 | |
| CGS 15943 | 105 ± 13 | 127 ± 18 | |
| DPCPX | 1,000 ± 160 | 1,100 ± 175 | |
| SCH 58261 | >10,000 | >10,000 |
Displacement of [3H]MRE 3008F20 was determined in the absence and presence of 100 μM GTP. KH and KL are the Ki values of the high- and low-affinity states for agonists, respectively. RHindicates the percentage of A3 receptors in the high-affinity state ± S.E.M.