Table 1.
Neuronal Uptake and Clearance Rates of [11C]Phenethylguanidines in Isolated Rat Hearta
compd | R1 | R2 | R3 | R4 | name | acronym | Kup (ml/min/g) | major clearance T1/2 (hr) |
---|---|---|---|---|---|---|---|---|
[11C]1a | H | H | H | H | [11C]phenethylguanidine (PG) | PG | 1.56 | 3.3 |
[11C]1b | OH | H | H | H | [11C]meta-hydroxy-PG | MHPG | 1.96 ± 0.13 | >102 |
[11C]1c | H | OH | H | H | [11C]para-hydroxy-PG | PHPG | 1.64 ± 0.15 | >45 |
[11C]1d | H | H | H | (-)-OH | [11C](-)-β-hydroxy-PG | BHPG | 0.42 | 22 |
[11C]1e | OH | H | H | (-)-OH | N-[11C]guanyl-meta-octopamine | GMO | 0.30 ± 0.02 | >152 |
[11C]1f | H | MeO | H | H | [11C]para-methoxy-PG | PMPG | 0.73 | 2.3 |
[11C]1g | F | H | H | H | [11C]meta-fluoro-PG | MFPG | 0.24 | 1.9 |
[11C]1h | H | F | H | H | [11C]para-fluoro-PG | PFPG | 0.63 | 4.4 |
[11C]1i | H | H | F | H | [11C]ortho-fluoro-PG | OFPG | 1.76 | 2.3 |
[11C]1j | OH | F | H | H | [11C]para-fluoro-meta-hydroxy-PG | 4F-MHPG | 0.72 ± 0.05 | >73 |
[11C]1k | OH | H | F | H | [11C]ortho-fluoro-meta-hydoxy-PG | 6F-MHPG | 0.49 ± 0.07 | >20 |
[11C]1l | I | H | H | H | [11C]meta-iodo-PG | MIPG | 1.10 | 2.4 |
[11C]1m | H | I | H | H | [11C]para-iodo-PG | PIPG | 0.56 | 1.9 |
For compounds with multiple determinations, Kup data are mean ± standard deviation (SD) and T1/2 is the fastest measured clearance rate for n = 5 independent determinations. Coefficients of variation (SD/mean) for these ranged from 7-14%. Single determination values can be expected to be within this range. Extraneuronal uptake (uptake-2) was inhibited in all studies by adding 54 μM corticosterone to the perfusate.