Table I.
Inhibition of FITC-APEC and Radioligand Binding to A2a-Adenosine Receptorsa
| Binding inhibition | |||
|---|---|---|---|
| Inhibitor | Ki (nM) vs FITC-APEC | (Hill) | Ki (nM) vs[3H]NECA [23] |
| NECA | 4.1 ± 0.1 | (1.90) | 10 |
| DPMA | 13 ± 3 | (0.97) | 4.4 |
| 2-CADO | 34 ± 14 | (0.89) | 63 |
| CHA | 195 ± 28 | (0.74) | 510 |
| R-PIA | 103 ± 14 | (0.60) | 120 |
| CV 1808 | 131 ± 62 | (1.10) | 120 |
| Theophylline | 59,000 | (1.60) | 25,000 |
| ARA-A | >100,000 | (—) | Inactive |
| 5'-GMP | >100,000 | (—) | Inactive |
a
Tissues were prepared and binding assays performed as described under Materials and Methods. Membranes were assayed in buffer containing FITC-APEC (50 nM) and varying concentrations of the listed compounds. Values (mean specific binding ± SE) were estimated using the equation Ki = IC50/1 + [L]/KD. Data are from at least three experiments using triplicate samples from each assay. Ki values could not be established for inhibition of FITC-APEC binding by ARA-A and 5'-GMP but were greater than 100,000 nM. Values for inhibition of [3H]NECA binding were obtained from previously reported data using rat brain membranes [23].