8-Phenyltheophylline

8-Phenyltheophylline is an adenosine receptor (adenosine receptor) antagonist. 8-Phenyltheophylline blocks adenosine-stimulated cAMP accumulation, inhibits tissue-selective cAMP hydrolysis, and antagonizes the inhibitory effects of adenosine. 8-Phenyltheophylline enhances apomorphine-induced rotational behavior in lesioned rats, reverses the analgesic effect of morphine in the rat hot plate test, and slightly enhances contractile responses of the atrium and ileum. 8-Phenyltheophylline can be used in studies related to unilateral nigrostriatal pathway injury^[1]. In Vitro:8-Phenyltheophylline (10 min) potently inhibits adenosine-stimulated cyclic AMP accumulation in rat hypothalamic slices, with a half-maximal inhibitory concentration (IC₅₀) of approximately 1 μM^[1].
8-Phenyltheophylline (0.5-25 μM) selectively inhibits cyclic nucleotide phosphodiesterase-mediated cAMP hydrolysis in rat erythrocytes and gastrocnemius muscles, and shows extremely low activity in rat adipocytes, abdominal aortas and brain extracts^[2].
8-Phenyltheophylline (10 μM) potently and selectively inhibits the high-affinity cAMP phosphodiesterase isozyme in erythrocytes of *Rattus norvegicus* (inhibition rate: 55%)^[2]. In Vivo:8-Phenyltheophylline (5-20 mg/kg; i.p.; single administration 30 minutes prior to apomorphine treatment) dose-dependently potentiates apomorphine (HY-12723)-induced rotational behavior in 6-OHDA (HY-B1081)-lesioned rats^[1].
8-Phenyltheophylline (10 μg; intrathecal injection; single bolus administration) reverses morphine-induced analgesia in the hot-plate test but not in the tail-flick test in rats^[3].
8-Phenyltheophylline (10 μg; intrathecal injection; single bolus) still reverses morphine-induced analgesia in the rat hot-plate test after degeneration of the noradrenergic descending pathway, but loses the ability to reverse morphine-induced antinociception in the rat hot-plate test after degeneration of the descending serotonergic pathway^[3].