Table 2.
Inhibition of [3H]PIA binding to cerebral cortex membranes by xanthine derivatives
| Xanthine | Inhibition [3H]PIA binding (Ki, nM)
|
||
|---|---|---|---|
| Rat | Calf | Guinea Pig | |
| 29 Theophylline | 12800 (10800–15300) | 13500 (7000–26000) | 24700 (19800–30800) |
| 30 8-Phenyltheophylline | 76 (58–98) | 7.6 (4.0–14.4) | 1540 (910–2610) |
| 31 8-p-Sulfophenyltheophylline | 1000 (770–1360) | 300 (190–270) | 10100 (7250–13950) |
| 32 8-Cyclopentyltheophylline | 510 (400–660) | 54 (42–69) | 1200 (980–1500) |
| 33 8-Phenylaminotheophylline | 5300 (3200–8900) | 1200 (500–2900) | 21700 (12800–36600) |
| 34 Caffeine | 44000 (31000–63000) | 44000 (27000–73000) | 47000 (36000–62000) |
| 35 8-Phenylcaffeine | 14700 (12200–17700) | 8800 (6300–12600) | 25200 (17800–35600) |
| 36 1,3-Dipropylxanthine | 710 (670–750) | 340 (230–510) | 1310 (1000–1720) |
| 37 1,3-Dipropyl-8-phenylxanthine | 10.0 (5.5–18.2) | 0.22 (0.07–0.69) | 20.9 (16.3–26.9) |
| 38 8-(p-Sulfophenyl)-1,3-dipropyl-xanthine | 140 (110–200) | 32 (20–52) | 810 (390–1650) |
| 39 1,3-Dipropyl-8-(p-H2N(CH2)2-NHCOCH2-OC6H4)-xanthine (XAC) | 1.3 (1.0–1.7) | 0.15 (0.09–0.24) | 16.5 (9.6–28) |
| 40 1,3-Dipropyl-8-cyclopentylxanthine | 1.2 (0.71–1.9) | 0.29 (0.21–0.39) | 3.9 (2.6–5.9) |
| 41 1,3-Dipropyl-8-cyclohexylxanthine | 1.4 (0.91–2.0) | 0.21 (0.11–0.43) | 4.7 (3.4–6.6) |
| 42 1-Propargyl-3,7-dimethylxanthine | 11000 (9000–13000) | 16400 (15100–17800) | 25800 (22400–29700) |
| 43 1,3-Dimethyl-7-propylxanthine | 19800(15200–25700) | 18200 (16200–20500) | 33300 (19000–58000) |
| 44 1,3-Dipropyl-7-methylxanthine | 3400 (3500–4400) | 2400 (1200–4700) | 6200 (4700–8100) |
| 45 3-Isobutyl-1-methylxanthine | 6200 (5000–7800) | 4400 (3700–5200) | 8600 (6200–11800) |
Binding of 1 nM [3H]PIA was measured at 37°C. Values are geometric means with 95% confidence limits from n = 3 experiments