Table II.
Potencies of Xanthine Derivatives at A2- and A1-Adenosine Receptors
| no. | Ra | A2 receptor:b KB, nM | A1 receptor:c Ki, nM |
|---|---|---|---|
| 1a | Me | 1900 | 70 |
| 1b | Et | 210 | 65 |
| 1c | Pr | 2100 | 13 |
| 2c | Pr | 2400 (1500–3900) | 50 |
| 3b | Et | 170 (75–370) | 140 |
| 3c | Pr | 135 (106–173) | 13 |
| 4b | Et | 73 (54–98) | 90 |
| 5b | Et | 48 (36–65) | 57 |
| 6a | Me | 40 (30–54) | 13 |
| 6b | Et | 21 (18–23) | 12 |
| 6c | Pr | 25 (21–30) | 1.2 |
| 7a | Me | 430 (260–720) | 27 |
| 7b | Et | 100 (60–170) | 9.3 |
| 8b | Et | 210 (190–230) | 58 |
| 9a | Me | 63 (57–68) | 42 |
| 9b | Et | 28 (15–51) | 25 |
| 10b | Et | 230 (100–540) | 180 |
| 11b | Et | 23 (17–30) | 9.4 |
| 11c | Pr | 37 (35–40) | 0.87 |
a
Substituent at the 1,3-positions (see Figure 1).
b
Antagonism of NECA-induced stimulation of adenylate cyclase activity in human platelet membranes. Values are means with 95% confidence limits from three separate experiments. Values for 2c, 6c, and 11c from ref 2; value for 1b from ref 14.
c
Inhibition of [3H]PIA binding to rat cerebral cortex membranes. Values are means from two separate experiments.